As I understand it, hydrated lime is only slightly soluble in water and the
solubility is inversely proportional with temperature. What is the actual
solubility of hydrated lime in water with temperature? Also, how is the
solubility of quicklime determined since quicklime reacts with water to form
hydrated lime and is not in its original form in a water solution?

Since magnesium carbonate is chemically very similar to calcium carbonate
why doesn't magnesium oxide and magnesium hydroxide have the exact same
chemical properties as calcium oxide (Quicklime) and calcium hydroxide
(Hydrated Lime)?

With regard to the NAFTA Certificate of Origin, what does the HS Tariff
Classification Number mean and what are the HS Tariff Classification
Numbers for quicklime and and hydrated lime? Also, what does the
Preference Criterion mean?

I have a slaker, or other type of lime handling equipment, that requires a
part that is no longer available or manufactured. Is there a company who
can make this part for me if I have the drawings/specifications, or if all
I have is the broken part(s)?

What is a Lime Slurry and are there other physical forms of hydrated
lime and water? Also, is there a formula that can be used in calculating the
amount of lime and water to produce a certain percent slurry?

When I called to place an order for lime by truck I was
told there was a shortage of trucks. All of the lime companies I
talked with also confirmed this. Why does this happen? Also, how do the
trucking companies maintain enough trucks to serve the lime market and what
can I do to help avoid these truck shortage situations?

When I order truck shipments of lime my lime supplier sets up the
trucking. Should I consider having my company handle the transportation
arrangements or should I continue to have my lime supplier handle this?

Why are all the Questions and Answers on the FAQS (Frequently Asked Questions)
web page displayed on single page, rather than on multiple pages of the website?

PRODUCT:

There are limestone deposits all around my location. Why isn't there
any high calcium lime available locally?

The term limestone can refer to both dolomitic limestone or
high calcium limestone. Most limestone deposits are dolomitic
limestone, which is a mixture of calcium carbonate and magnesium carbonate
in a general ratio of 40-60%. High calcium limestone is generally
considered to be in excess of 90% calcium carbonate. Nature does create
predominantly limestone deposits composed of predominantly calcium
carbonate, however, these locations are considerably fewer than those of
dolomitic limestone. Although both carbonates undergo the conversion to
oxide in the kiln (CaO and MgO) there is an important, fundamental
difference in their reactivity with water. Calcium oxide will react
readily with water at normal temperatures to produce calcium hydroxide and
an excess of heat (exothermic) whereas magnesium oxide requires special
conditions to convert to magnesium hydroxide. Any magnesium oxide will
remain unreacted in water, resulting in additional grit. If kilns were set
up to process dolomitic limestone into "quicklime", approximately 40% of
the product (the MgO portion) will not react with water significantly,
resulting in about 40% grit.

This is quicklime, which is chemically known as calcium oxide. Because
quicklime generates a lot of heat (exothermic) when reacting with water to
form hydrated lime (calcium hydroxide) it has been commonly known as "hot
lime". Hydrated lime will not generate heat when mixed with water since it
has already been converted to the hydrated form.

This is because of the different fuels used to heat the limestone
(calcium carbonate) to convert it to quicklime (calcium oxide). Many
suppliers use pulverized coal and a mixture of pet coke which can result
in a slight grayish color to the quicklime due to the exposure to the
fuel. You'll notice that a pebble of quicklime, when split, will appear
white inside since this area has not been exposed to the burning fuel
directly. Generally, The tint of the quicklime has no significant
bearing upon the reaction of the quicklime with water. This is because
the amount of material associated with the color is insignificant. The
exception would be if the quicklime were "overburned", which could
decrease the reactivity.

This term refers to quicklime that has been subjected to excessive heat.
The term really means "over heated quicklime". The term "burning"
generally refers to oxidation, which is the process of a material
chemically reacting with oxygen (combustion, rusting, etc). In the kiln,
the limestone is simply subjected to a high temperature (ranging from
1850 to 2450o F for high calcium limestone) which results in
the dissociation of the limestone into calcium oxide and carbon dioxide.
For the most part, the limestone going into the kiln is in pebble form.
Since the pebbles are the result of the crushing of the limestone rock,
they are irregular to a degree and vary in sizes. In heating the
limestone pebbles a compromise has to be reached between heating the
larger pebbles enough to convert them entirely, and not overheating the
smaller pebbles. Limestone is a porous rock, so the carbon dioxide gas
escapes through the pores of the rock. If the pebble is subjected to
too much heat, the surface can tend to shrink, which results in a delay
in the conversion from calcium carbonate to calcium oxide. Overburned
quicklime tends to react at a slower rate than ideally burned
quicklime.

This is generally determined by the volume/usage (tons) of lime used. From a practical standpoint it is often the case
that those companies who utilize a truckload or more of hydrated lime a month (300 tons, or 600,000 lbs) can benefit
from using quicklime, rather than hydrated lime. Often the F.O.B. producer plant price of bulk hydrated lime is close
to the price of bulk quicklime. Bulk hydrated lime, however, has only a CaO equivalent of 76%. This percentage comes
from the calcium oxide molecular weight of 56 divided by the calcium hydroxide molecular weight of 74 (56/74=76%). As
a result, each truckload of hydrated lime is composed of 24% chemically combined water. If the usage (tons) is high
enough, the cost of a slaker (reaction vessel for converting quicklime to hydrated lime) can be offset by the higher
potency of the quicklime. One convenient way to visualize quicklime is that it can be thought of as the same product
as hydrated lime, but with the chemically combined water removed.

Most companies who buy quicklime are generally using a fairly large volume of lime, so they create their own hydrated
lime by reacting it with water at their plant. If the usage is relatively small a company will often buy hydrated lime,
which is quicklime already reacted. For calculation purposes you can consider that a truck of quicklime, ideally, equals
1.32 trucks of hydrated lime. Another important consideration is that, generally, using quicklime requires that you use
a slaker, whereas you can use a simple mixing tank with agitators to use hydrated lime. The cost of a lime slaker is
generally higher than that of a lime mixer.

Reaction (1):
Calcium oxide (quicklime) is produced by the thermal dissociation of calcium carbonate (limestone).
The weight ratio is such that 100 tons of pure calcium carbonate will produce 56 tons of calcium oxide.

Reaction (2):
The reaction of calcium oxide with water to produce calcium hydroxide is very energetically favorable, so the exothermic
reaction takes place spontaneously in the presence of significant amounts of water. If the available moisture is limited,
as in the humidity in the air, the quicklime will act as a desiccant and react with the air moisture, a process commonly
referred to as air slaking. To produce a dry hydrated lime you would simply limit the amount of water added to
exactly 18 tons of water to the 56 tons of quicklime, which will then result in 74 tons of dry hydrated lime. Water added
in excess of that required to meet the affinity of CaO for water will produce a paste, followed by a slurry, and then a
Milk of Lime.

Reaction (3):
The reaction of carbon dioxide gas with calcium hydroxide occurs relatively slowly from carbon dioxide in the air. However,
if the carbon dioxide is dissolved in water, (see Reaction (a) below), then carbonic acid is produced. As in the
traditional acid-base type reaction the product of the reaction of carbonic acid and calcium hydroxide is water and the salt,
calcium carbonate, which precipitates from solution. (See Reaction (b) below). Bubbling carbon dioxide through a
solution of calcium hydroxide is used in various industrial and chemical processes to remove excess calcium hydroxide from
solution, and also to produce Precipitated Calcium Carbonate, which is used as a whitener and filler in the Pulp
and Paper Industry, as well as other industries.

Reaction:

(a) CO2↑ + H2O →
H2CO3
(b) H2CO3 + Ca(OH)2 →
CaCO3↓ + 2H2O

Note: In all formulas above, the ideal molecular weights are used. In actual practice, however, the commercial limes
used are not 100% pure nor are the reactions ideal. The values indicated should be considered only as approximations.

Why would I not want to simply buy lime slurry, rather than buying
quicklime or dry hydrated lime (in bulk or bags) to make my own
slurry?

For some purposes using a lime slurry is fine. However, there are a
number of considerations to be aware of. First, consider that it takes
1.32 trucks of hydrated lime to equal a truck of quicklime (weight
ratios). If the slurry were 20% solids, it would take 5.0 trucks of
slurry to equal one truck of dry hydrated lime, or 6.6 trucks of slurry
to equal one truck of quicklime. In addition, you will have to factor
in the freight cost for hauling a truck with 80% water in it. Quicklime
and dry hydrated lime arrive in pneumatic trucks, and the lime is pumped
into silos. Slurry comes in a slurry truck, which is then pumped into
an on site portable slurry tank, or slurry tank in the plant. The
slurry has to be constantly agitated to avoid the settling of the lime.
Another consideration involves the availability of slurry. All of the
major lime companies produce quicklime and most produce dry hydrated
lime. Only a few are involved with lime slurry, which limits the
sources available. All of these things have to be taken into account in
considering slurry rather than quicklime or dry hydrated lime.

Lime is used to neutralize acids, which raises the pH. How does this
take place?

Most quicklime is converted to hydrated lime before using. Hydrated lime
is chemically known as "calcium hydroxide" and is a strong base. The
reaction of an acid and a base produces a "salt" and water, so a base
"neutralizes" an acid. Simple examples of this are the reactions of
hydrochloric acid (HCl) with sodium hydroxide (NaOH) and with calcium
hydroxide (Ca(OH)2):

Typical Acid-Base Reactions

HCl + NaOH → NaCl + H2O2HCl + Ca(OH)2 →
CaCl2 + 2H2O

The products of this reaction are water (H20) plus the salts:
sodium chloride NaCl) or calcium chloride (CaCl2). To those
less familiar with chemistry, the term "salt" is generally thought of as
NaCl (table salt), however, a "salt" should be thought of as the product of
an acid-base reaction. When an acid is in a water solution it dissociates
into a cation (H+) and an anion (Cl-). The term pH
refers to the concentration of hydrogen ions (H+). As these
ions are combined with the (OH-) from the base, the number of
hydrogen ions (H+) decrease which results in the neutralization
of the acid. The pH of a solution can range from 0 to 14. A pH of 7.0 is
considered to be completely neutral (deionized water). So a solution that
is acidic has a pH of less than 7.0 and a solution that is basic has a pH
above 7.0. Lime is a strong base and an excess of lime can quickly produce
a pH above 12. It can also be seen, as shown in the reactions above, that
a molecule of calcium hydroxide (Ca(OH)2) will react with twice
(2x) as many molecules of hydrochloric acid
(HCl) than sodium hydroxide (NaOH) does.

I keep hearing the term Pebble Quicklime and sometimes see the
letters QL and PBQL. Why is this terminology used and
what does it mean?

Commercial quicklime is commonly produced in rotary kilns where pebbles of
high calcium limestone are transported through the kiln and converted into
quicklime (calcium oxide). Initially, the limestone is quarried into
boulders, which are then broken down further and taken to a crusher. After
the crushing process, and a further sizing process, the pebbles go into the
kiln. When they exit the kiln they may be crushed further and sized, but
in any case, the pebbles of quicklime are produced in generally two
size ranges that have the trade names of Rice and Medium size
quicklime. Pebbles that are too large go back to the crusher while
quicklime that is too small to be sold as Rice size quicklime is
either sold as Granular size quicklime or is used to make hydrated
lime in a plant that is usually found adjacent to the kiln operation.
(The general designation QL is commonly used
for quicklime as the designation of HY for
hydrated lime. The designation of PBQL is
often used for pebble quicklime as opposed to Granular or Pulverized sized
quicklime.)

How much less lime will I use if I use quicklime rather than bulk
hydrated lime, and at what point is this practical?

This is easy to determine. When hydrated lime is produced from quicklime
it is a "complete" reaction in that all of the water chemically combines
with the quicklime:

CaO + H20 --->
Ca(OH)2 + Heat

The molecular weight of quicklime, CaO is 56 and that of hydrated lime,
Ca(OH)2 is 74. (Calcium, Ca=40, Oxygen, O=16 and Hydrogen,
H=1)

The best way to think of "molecular weight" is a "weight ratio". Once
quicklime is added to water it converts to hydrated lime so you are
essentially comparing the same product in different forms. In the simplest
form 56 lbs of quicklime is equivalent to 74 lbs of hydrated lime. Another
way to view this is to take your current hydrated lime usage (tons) and
multiply it by 0.757 to come up with the approximate usage of quicklime
equivalent to your hydrated lime usage. This factor comes from dividing the
molecular weight of quicklime (56) by that of hydrated lime (74), which
equals 0.757, or 75.7%.

Whether or not it is practical to switch from using bulk hydrated lime to
using quicklime generally depends upon the amount of lime you're using and
your willingness to purchase a slaker. (Slakers insure that you have
complete, intimate mixing/reacting of water with the quicklime, which is
very important since the reaction is exothermic and produces steam). If
you're currently using bulk hydrated lime you already have a storage silo
so purchasing a silo won't be an issue unless you want to increase your
storage capacity. If you're producing a lime slurry it's likely that
you'll require a slaker rather than the current mixer you've been using.
As a general rule bulk hydrate seems to be used for requirements of up to
1-2 trucks a month (300 to 600 tons/year, a truck holds approximately 25
tons). Some customers will use quicklime if they're using only
100-200 tons/year, but generally quicklime is not considered until
somewhere in the 300-600 tons/year range. In any case, the costs vs.
savings factors need to be carefully evaluated prior to making the decision
to switch from bulk hydrated lime to quicklime, and each customer's
requirements will be different.

I need to use hydrated lime but am not sure whether I should get it
in bags or in bulk. What are some of the advantages and disadvantages of
bags vs. bulk?

This primarily depends upon how much hydrated lime you intend to use,
and whether or not it will be used in multiple locations. Both bagged
and bulk hydrated lime serve a purpose, so it's important that you have a
clear idea of your long-term plans with lime.

BAGGED: If your are a distributor of hydrated lime you will almost always
require only bagged hydrated lime. If you are a lime user, and require a
sizeable amount of lime, but have to transport it to multiple locations
(such as individual well sites, etc.) your only option is probably hydrated
lime in bags. Generally, customers who are currently using bagged hydrated
lime in their process do not require a lot of lime. In some cases bagged
hydrated lime has an advantage because each bag is 50 lbs which allows it to
be used in batch preparations where a certain number of bags of hydrated lime
are added to the mix/batch. Advantages: You only require storage space
and a mixing tank to prepare the slurry. Disadvantages: the price
(bagged hydrated lime is more expensive), the unloading (pallets of lime
have to be removed from the truck by a forklift) and the handling (each
bag has to be handled by a worker).

BULK: Bulk hydrated lime is usually used by customers who have a higher
usage requirement. Your long term projected usage of hydrated lime needs
to be taken into account in considering bulk hydrated lime. If the
usage is expected to increase, it may pay to invest in the capital
equipment to use bulk hydrated lime right at the start. Some customers,
who are in the process of implementing a new lime slurry operation, will
start with bagged hydrated lime, then switch to bulk once the operation
gets going. Advantages: the price (bulk hydrated lime costs less
than bagged hydrated lime), the unloading (the lime is delivered via a
pneumatic tank truck which blows the product into the silo, so the
customer has no labor in unloading), and the handling (the lime is
automatically handled from the silo to the slurry preparation).
Disadvantages: Initial capital investment (you will require a
lime silo, feeder and metering equipment to control the feed of the
hydrated lime to the mixing tank).

What is the difference between Limestone and Lime? Also, I hear
the terms Aglime and Dolomitic Lime used a lot. How do they
differ from limestone and lime?

This question comes up quite frequently and is caused by a popular use of the
term LIME interchangeably for
"limestone" and "lime" especially in the agricultural market.
From a practical standpoint it's likely that this will continue in the future,
so it's very important to know when a person says they use "lime", whether they
mean "limestone", which is rock, or do they really mean "lime", which is a
chemical in the form of the oxide or hydroxide. (From a chemistry standpoint,
lime is a chemical base.)

Limestone:
Although limestone is often referred to as "lime" it is actually a "stone or
rock", either naturally occurring in mineral deposits or, when physically
processed, in various size pebbles, crushed, ground or pulverized. The term
limestone generally refers to calcium carbonate, CaCO3 and magnesium
carbonate, MgCO3, which are usually found together, to some degree,
in various proportions. The term Dolomitic Limestone
general refers to limestone deposits with a much higher percentage of
MgCO3 than is found in high calcium limestone deposits.
(Cheney Lime & Cement Company produces quicklime, CaO from the calcination of
deposits of high calcium limestone in Shelby County, AL. This quality of
limestone is required to produce the high calcium quicklime and high calcium
hydrated lime products we supply.)

Lime:
In the correct use of the term, lime is actually a "chemical" which is in
the form of calcium oxide, CaO (quicklime) and/or magnesium oxide, MgO which
is produced from the high temperature process of calcination which takes place
in a lime kiln. Lime also refers to calcium hydroxide, Ca(OH)2 and
magnesium hydroxide, Mg(OH)2 which are the hydroxides produced from
the reaction of the oxide and water. In the case of calcium oxide, CaO the
reaction occurs readily and is highly exothermic. Both Ca(OH)2 and
Mg(OH)2 are chemical bases.

Aglime: Generally, Aglime (sometimes referred to as
Agstone) is a dolomitic or high calcium limestone that is finely ground to
enable it to neutralize soils that are acidic. Although limestone is considered
relatively inert, it can be attacked by a strong acid, or a weak acid over time,
and will neutralize the acid. If the acidity is quite high, then either
quicklime or hydrated lime is usually used.

Hydraulic Lime and Hydrated Lime have basically the same chemical
composition, however, hydraulic lime has its initial setting with water
(similar to cement) and a second setting with recarbonation (the absorption
of CO2). Hydrated lime does not set with water and only undergoes
recarbonation. Cheney Lime & Cement Company produces a type N hydrated lime,
which is used chiefly for its chemical characteristics. Hydrated lime that is
used for construction purposes (stucco, etc.) represents only modest quantities
compared to the chemical uses.

I've heard of a Type N and a Type S hydrated lime. What is
the difference between the two and can I use a Type N hydrated lime when
the requirement calls for a Type S?

The "N" in the Type N hydrated lime refers to Normal and
the "S" in Type S hydrated lime refers to Special. When
thinking about these two types of hydrated limes the simplest way to think of
them is that Type N is used primarily for its chemical nature and Type S is
used in construction. The reason why a Type S is different involves
milling (physical size) characteristics, etc. However, a key factor involves
how the hydrated lime is produced.

In both types of products the process starts with quarrying limestone
CaCO3 (calcium carbonate), breaking it up into pebbles, then
heating (calcining) the pebble to a high temperature which results in
CaO (calcium oxide) being formed as well as CO2 (carbon dioxide).
Hydrated lime is produced from the exothermic reaction of CaO (calcium oxide)
with H2O (water) to produce Ca(OH)2. In nature, high
calcium limestone does have some MgCO3 (magnesium carbonate) in it.
In the lime kiln this undergoes the same decomposition reaction that calcium
carbonate does, to produce MgO (magnesium oxide). Under normal temperatures
and pressures MgO is slow to react with water, so it generally remains in the
"grit" that is normally found in a Type N hydrated lime. Eventually, this MgO
will react slowly with water, over time, to produce Mg(OH)2, however
the process is quite slow, and generally the grit is either removed routinely,
or is of no consequence in the process of using the Type N hydrated lime.

In construction things area bit different. If this "grit" is part of a product
manufactured with hydrated lime, over time, it can become a problem because, as
the residual MgO reacts with water, even though very slowly and over a long
period of time, the magnesium hydroxide produced expands when forming, taking
up more space. In companies using autoclaves in their process, the conversion
of MgO grit to Mg(OH)2 is accelerated.

In producing a Type S hydrated lime, the hydration process of CaO & MgO is
completed under elevated pressure and temperature conditions to make certain
that the conversion of all MgO to MgOH2 is assured. Consequently,
there should be little, if any, expansion of the products produced with Type S
hydrated lime. Because the the process of producing a Type S hydrated lime
requires additional steps, the cost is higher. Also, there are fewer producers
of a Type S hydrated lime then Type N, also adding to the possible higher cost.
However, the potential negative consequences of substituting a Type N product
for a Type S can be expensive when it requires re-doing the original work.

What about companies using CaO in their production
process? Some companies use CaO (quicklime) is the production of
construction products, such as sand lime bricks. In that process, the quicklime
is being hydrated and any grit that contains MgO will be contained in the
product. When the "green" bricks are autoclaved, they are subjected to high
pressures and temperatures, and any MgO in the bricks will be converted
Mg(OH)2 which can then cause "cracking" as the Mg(OH)2
expands during formation. There are some potential ways to get around this.

The simplest way to accomplish this would be to produce a slurry of
hydrated lime, in which all of the grit is removed, and as a result, all of
the MgO "grit" would be removed.

Another way would be to subject the quicklime and sand combination to
pressures and temperatures, earlier in the process, to make certain that all
of the MgO "grit" has converted to Mg(OH)2. This can be accomplished
with a temperature of 180oC.

Finally, the specification for the quicklime used could be stated such
that the MgO contained be less that a certain percentage. It's my understanding
that it should be below 1% if possible, but definitely 2% or below. A 1% MgO
can cause an expansion of 0.5% in the autoclave. (A too low MgO% requirement
is likely to not be feasible economically since a plant would like to be able
to use a regional commercial grade quicklime. It would be likely to be
less expensive to modify the process, and have a larger number of potential
suppliers for competitive reasons, than to pay to have a "chemical grade" type
quicklime.)

Why does the price of quicklime increase when I know that there are
still enormous deposits of high calcium limestone available to be produced
into quicklime?

It's true that there are huge supplies of high calcium limestone in the
quarries that lime producers own. The supply of limestone, however, is not
the primary determining factor in what the market price of lime will be. To
understand this, keep in mind that all of the quicklime that is in the lime
market (hydrated lime is produced from quicklime) came from high calcium
limestone that had to go through kilns to be converted to quicklime. A new
kiln is a major undertaking for a lime company, both financially and with
regard to state and federal regulations. As a result, lime companies try
to anticipate the lime market to make certain the new kiln will either meet
existing demands, or those anticipated in the reasonably foreseeable
future. If the lime market is "soft", and future prospects for the economy
uncertain, it's unlikely that a new kiln will be brought online until
things have improved. Eventually, the demand will grow to meet the
existing lime production capacity, yet a new lime kiln may still not be
brought online. In fact, during periods when lime demand is very slow,
existing kilns may be idled to bring production more in line with existing
demand. In any case, the critical path is that the number of "kilns in
operation" determines the market; not the supplies of high calcium
limestone.

How does the availability and quality of high calcium limestone
deposits affect the price of quicklime?

Although the number of kilns in operation is a major determining factor in
lime price, the limestone deposits and quarrying operations play a very
significant part, principally due to their effect on bottom line production
costs. If the limestone in the quarry is found in a deposit of consistent
quality, and is relatively easy to reach, the quarry costs are lower. If
the quality of the deposit is inconsistent, there is an increase in the
amount of selective quarrying that has to be performed. Also, if the
limestone deposit has to be mined underground, as opposed to an open
quarry, the costs increase. As the limestone that is located closest to the
kilns is depleted, limestone has be to be brought in from further
distances, which results in an increase in transportation costs. All of the
factors in limestone deposits and quarrying have a direct impact on the
bottom line cost to produce quicklime. This has a significant effect on the
quicklime price the lime producer can offer to the market and still expect
to realize a reasonable profit.

Will forming a buying cooperative, or buying from an existing one, always
guarantee that I'm paying the lowest price for lime?

Forming a cooperative does clearly offer some advantages. (1) Having a single
cooperative member's purchasing department handle all of the bids for all of
the members provides a savings in both time and personnel. (2) Buying as a
cooperative group does increase the total volume of lime used, increasing
the purchasing power of the members and can result in a reduction in the lime
price. (3) Also, buying within the cooperative enables the smaller members to
increase their market share and purchasing power. However, there are a number
of reasons why cooperatively buying may not provide the best price despite
the higher total market share.

The assumption is that increasing the market share will always provide
the best price. This works to a point, however, when a cooperative begins
to get too large the number of lime suppliers able to supply the high
volume decreases, thus competition is actually reduced. Eventually, a
cooperative can reach a point where only one lime supplier can supply them,
which leaves them in a somewhat vulnerable position.

All price increase projections for the year have to be given to all
of the members at the same time. When cooperative members (especially
municipalities) are bidding individually throughout the year a lime
supplier has the opportunity to "sharpen their pencil" on the next bid,
if they lose the current bid. When bidding on a cooperative, the approach
is "all or none", consequently, a lime supplier has to factor in any
potential price increases and lock them in for a year.

Large cooperatives tend to discourage the introduction of new
lime competitors because all of the business is "locked up". If a
potential lime supplier does enter the market and is able to win the
cooperative bid, they have no assurance that they will have the bid the next
year, even if there are optional extensions to the contract.

Generally, moderately sized market share cooperatives appear to successfully
gain pricing advantages and do not seriously deter competition. Extremely
large cooperatives, on the other hand, appear to offset the cooperative
advantages by deterring competition and the introduction of new lime
competitors.

We are trying to determine if it would be better for us to go with a multiple
year contract for our lime requirements, rather than a single year. What are
the advantages and disadvantages?

Many industries and municipalities have an annual contract for lime. One
of the advantages of this type of contract is that it forces a lime user's
purchasing department to review the current market for lime in a one year
cycle. Another important advantage is that it keeps all of the lime
companies interested since they have an opportunity each year to go after
the business.

Contract Extensions: Municipalities, and some industries, will provide for
annual extensions, sometimes up to three years, if both parties are in
agreement. The general assumption is that holding the price for another
year is always good for the organization. This is not always the case. In
some instances, a lime company has recently lost a contract and needs to
replace that lost tonnage. In those cases they may bid more competitively
to replace the lost business. Also, the prices in the lime market do
follow cyclical patterns as a result of changes in the economy, as well as
the introduction of new kilns. Those industries and municipalities, who
have nearly automatic contract extensions, often miss out when the market
price does decline.

Multiple Year Contracts: When considering the duration of a lime contract
it's often appealing to try to lock in a price for two or three years, with
limited escalations in price being allowed on an annual basis. In addition
to the price advantages, the purchasing department reduces the number of
RFQs (request for quotes) that it has to be involved with. The lime user
feels that they've locked in a supply of lime at a predictable price,
however, what often happens is that the lime users, with the three year
contract, are "out of the loop", with regard to market changes. Since they
tend to become identified with a particular lime supplier they may find
themselves removed from the "active prospects" list of other lime
companies, which indirectly tends to reduce competition. Some companies,
who have two and three year contracts, may also find themselves in a
difficult situation in a tight lime market since a lime company is less
interested in helping out a lime user who offers little or no opportunity
for future business.

Recommendation: Whenever possible, an annual (twelve month) time frame
will often provide the best contract period for many businesses. The lime
user will be monitoring the market for lime, at least on an annual basis,
and the current lime supplier will always have to "be on their toes" with
regard to price, service and the lime market. Most successful lime users
want to make certain they're paying a fair price for their lime to insure
that they have good, dependable suppliers. If an option for multiple years
is needed it's generally best to have annual extensions, subject to
approval by both parties. This allows the lime user to avoid multiple years
of a high priced lime in a declining market, and allows the lime supplier
to limit their exposure to a low price in a rising market. The downside to
an annual contract is that it does require that the purchasing department
monitor the price of lime more frequently.

Lime companies refer to a "Typical Chemical Analysis". What does this
mean and why is it not referred to as a specific chemical analysis like the
reagent grade chemicals I buy?

All industrial lime is produced from quarried limestone (or in some cases
oyster shells), which has naturally occurring impurities in it. Many
companies wash the stone before in goes into the kiln, however, any
impurities in the limestone itself will appear in the quicklime. Much of
the control of the quality of the quicklime can be affected by how well the
material is quarried. The vein of limestone being quarried is constantly
monitored to insure that only the highest purity is selected for the kiln.
The quicklime produced is chemically analyzed, based upon standard
statistical sampling procedures, but the chemical analysis will vary to a
degree according to the way nature left the limestone deposit. This is why
most companies refer to a "typical chemical analysis." There are minimum
and maximum chemical limits to the various components of the lime, but
within these limitations the chemical analysis will always vary to some
degree. (Note: Lime can be produced from oyster shells, which have a very
high purity of calcium carbonate, however, this source of kiln material is
declining, having been almost completely replaced by quarried
limestone.)

What are the standard tests used to determine the percent of available
lime (CaO%) of quicklime and how do they differ? (ASTM C25 and AWWA
B202)

The two most widely used standard tests for available lime, used in both
the private and public sectors, are the ASTM C25 (American Society for
Testing and Materials standard) and AWWA B202 (American Water Works
Association) tests. Both of these tests use the Rapid Sugar Method
with the only significant difference between them being the normality of
the acid solution and the sample weight. Both tests require a specified
sample weight and specified acid normality such that 1 ml of the volume of
acid used equals 1% CaO. This makes it convenient for lab personnel since
they can simply read the number of milliliters (ml) of acid used from the
burette, which is then equal to the available lime percentage (CaO%). (Lime
users and producers may modify the test slightly with regard to the sample
size and acid normalities. In those cases the available lime percentage is
determined by simple calculations. See Modified Procedures shown
below.)

Acid Normality and Sample Size: In the case of the ASTM C25 test,
a 1.000 N HCl is used, which results in a requirement of exactly 2.804
grams of the sample of calcium oxide (CaO). In the case of the AWWA B202
test, 0.1782 N HCl acid is required and the sample must be exactly 0.500
grams. (The acid solution for the AWWA B202 test is usually prepared by the
lab personnel since a commercial, standard solution at 0.1782 N is not
readily available.) Care must always be taken in preparing any standard
solution to insure that it is as accurate as possible since an incorrect
acid normality will result in inaccurate CaO% determinations. Both the
purchased and prepared standard solutions should be periodically checked to
insure that they are accurate.

A Word About Quantitative Lab Procedures:
All of the tests for Available Lime CaO% are Quantitative tests.
The preservation of the sample throughout the lab procedures is absolutely
essential. Here are some important things to keep in mind about the Available
Lime CaO% chemical test:

Weighing the Sample:
The lime sample should be weighed in a small glass container (such as
a 50 ml beaker or dish) whose weight has tared out. (The container to weigh the
sample should not be aluminum. Lime reacts with aluminum, and since you will
be washing the initial sample holder with water you will want to avoid any
potential aluminum-lime reaction.)

Rinsing the Sample Container:
Once the lime sample has been dumped from the 50 ml beaker into the flask, a
wash bottle should be used to rinse the beaker to insure all of the sample is
in the flask.

Always use distilled CO2-free water:
In all aspects of the Available Lime CaO% test it is important to always use
distilled CO2-free water. The use of distilled water
is standard for all chemical tests to avoid impurities in tap water as well
as potential side reactions. With regard to making sure that you are
using CO2-free water, there are two important reasons for this.

Calcium hydroxide, Ca(OH)2 reacts with dissolved carbon dioxide,
CO2 to produce calcium carbonate, CaCO3. This will reduce
the Available Lime CaO%. (This is similar to the well-known commercial process
to produce PCC-Precipitated Calcium Carbonate by bubbling carbon dioxide through
a solution of calcium hydroxide.)

Carbon dioxide, CO2 dissolved in water produces carbonic acid,
(H2CO3) which is a weak acid that will neutralize some of the
Ca(OH)2 and result in a loss of Available Lime CaO%

Titration:
Before titrating the sample, the inside walls of the flask always need
to be rinsed to insure that none of the sample is on the walls.

Effect of Loss of Some of the Sample:
Keep in mind that, in the case of the AWWA B202 0.500 grams sample every
0.005 g lost in the lab procedure represents a drop of 1% in the Available
Lime CaO%. In the case of the ASTM C25 2.804 grams sample, every 0.028 grams
lost represents a drop of 1% of Available Lime CaO%.

A Word About Qualitative Lab Procedures: The use of the Phenolphthalein is
as an indicator of a basic solution. In a basic solution Phenolpthalein turns
pink. In the titration process, once all of the Ca(OH)2 has been
neutralized, the color disappears. This is a qualitative test in that it simply
indicates whether the solution is basic (pink) or acidic (clear). 4-5 drops of
Phenolphthalein are put into the sample solution, however, the amount is not
critical.

GENERALIZED TEST PROCEDURES:

The laboratory steps in the ASTM C25 and AWWW B202
are very similar: (Note: all of the water used should be CO2-Free Water.)

Sample Weight: The sample of quicklime
(CaO-Calcium Oxide) is pulverized, then a 0.500 g sample (AWWA) or 2.804 g
sample (ASTM) is weighed out and measured into a 250 ml flask with 10 ml of water (AWWA),
500 ml flask with 40 ml of water.(ASTM)

Boiling/Reaction:
The flask is placed on a hot plate and a specified amount of additional boiling
water is added (50 ml, ASTM & AWWA). The flask is swirled and boiled for a minute,
then removed from the hotplate.

Cooling & Sugar Addition: The flask is placed in
a cold water bath to cool it to room temperature.
This is done to maximize the solubility since the solubility of lime is inversely
proportional to temperature. Sugar is added (ASTM 40 grams, AWWA 15-17 grams),
then the flask is swirled and allowed to stand for 15 minutes, with
periodic additional swirling to allow the sugar and lime reaction to take
place. (Mechanical stirring devices can be used.)

Titration: Phenolphthalein solution is added as
an indicator, and the sample is titrated with the HCl-hydrochloric acid,
0.1782 N (AWWA), 1.0000 (ASTM) until the first complete disappearance of the pink
color (AWWA), or in the case of the ASTM C25 procedure, the first disappearance
of color that lasts for at least three seconds. (Note: the 3 second difference
between the two tests could result in a slight, but minimal difference in test
results.)

AVAILABLE LIME CaO% DETERMINATION:

Burette Reading Option for CaO%:
If the exact acid Normality and exact sample weight for each test (ASTM or AWWA)
are maintained, then number of ml of acid used = the CaO% (i.e. 94 ml acid used = 94% CaO).
Below is a summary of the standard ASTM C25 & AWWA B202 formulas, as well as a modification
of the AWWA B202 formula for a different acid Normality and sample weight.

*Note: The test was modified so that a commercially available 0.2000 N HCl can be used,
rather than the 0.1782 N HCl, to avoid the potential errors in the repeated lab
preparation of the 0.1782 N HCl acid. (The sample weight required becomes greater
as a result of the increase in normality of the HCl acid.)

(2) If 0.2000 N HCl is used, and the sample weight (W) is always 0.500 grams,
then 0.561/W = 0.561/0.5000 = 1.122, and the formula can be reduced to:Volume of 0.2000 N HCl used (ml) x 1.122 = Available CaO%.

Are these standard test procedures ever modified by lime
users and producers? The answer is yes, however, the only thing that is
usually changed is the sample size and/or the normality of the acid. The
lab procedures, including the addition of sugar to increase the solubility
of calcium hydroxide, are not changed. Keep in mind that both the
ASTM C25 and AWWA B202 tests are designed to enable the lab personnel to
read the available lime percentage from volume of acid used in the 100 ml burette.

The drawback to this is that the sample must be weighed to a very specific weight.
All forms of quicklime (pebble, granular or pulverized) immediately begin to undergo
air slaking when exposed to any moisture in the air. This simply
means that the moisture in the air reacts with the quicklime to form
calcium hydroxide. This process occurs all the time, but has its greatest
effect when the sample has been pulverized to a powder. The surface area
of the quicklime is increased dramatically, which increases the rate of air
slaking. Weighing the sample to a very specific, designated weight
requires the lab personnel to take extra time in weighing, during which air
slaking of the sample is occurring. Dependent upon the extra time
required, the sample weight can change. Care should always be taken to
insure the sample is weighed as quickly as possible.

To minimize air
slaking, a sample can be weighed exactly, at a weight close to the
"targeted weight", then titrated with a commercially available, standard
solution. The lab test procedures will be the same, however the available
lime (CaO% ) will need to be determined by calculation, using the amount of
acid used and the exact weight of the sample. Lime users and producers
will often modify the test in this way since it will generally produce more
accurate results, however, you do lose the convenience of simply reading the
available lime percentage (CaO%) as the milliliters of acid used.

Why is sugar added when running the standard titration for the percent
of available lime (CaO%) in quicklime? (ASTM C25 and AWWA B202)

The reason that sugar is added to the sample of quicklime after it has been
added to water, is to increase the solubility of calcium hydroxide that was
formed from the reaction of water and quicklime. This allows the lab
technician to titrate quickly and is the reason the test is referred to as
the Rapid Sugar Test for Available Lime.

The solubility of calcium hydroxide in water is quite low, with a range of
0.185 grams per 100 grams saturated solution at 0o C to 0.071
grams at 100o C. (Note that the solubility decreases with an
increase in temperature.) As the sample is stirred, a suspension of calcium
hydroxide is maintained (milk of lime). As you titrate the calcium
hydroxide in solution, more will dissolve. Since most of the calcium
hydroxide exists as a solid in suspension, it cannot be titrated until it
has dissolved (gone into solution.) The titration process itself involves
a reaction of the acid with calcium hydroxide in solution and will consume
lime, allowing more lime to go into solution. However, this process can be
speeded up significantly by the addition of sugar. When sugar is added, an
intermediate product is formed, calcium sucrate (calcium hydroxide saccharate)
which is significantly
more soluble than calcium hydroxide. For example; the addition of 35 grams
of sugar will increase the solubility of the calcium hydroxide from 0.159
to 13.332 grams per 100 grams of saturated solution at 25oC;
which is a solubility factor increase of 84.

What happens if you don't add the sugar as prescribed in the test? The acid
has to be added relatively slowly to allow the calcium hydroxide that is
still in suspension as a solid, to dissolve as calcium hydroxide that is in
solution is neutralized. The titration procedure requires that you add
acid until the first disappearance of color that lasts for three seconds.
If you've inadvertently added too much acid you've effectively created a chemical
"buffer". With excess acid introduced, the phenolphthalein pink color will
disappear, and the excess acid will react with any calcium hydroxide going
into solution with the result that the disappearance of color can persist
for three seconds, indicating an incorrect end to the titration. The amount
of acid used may be determined to be less than it should be and the
resultant calculation (or reading from the burette) will indicate an
available lime percent lower than the true value.

A number of companies titrate the calcium hydroxide without adding sugar
and are comfortable with this. The addition of sugar in the standard test
procedure was developed to insure that the endpoint of the titration could be
reached as quickly and accurately as possible, thus providing the greatest
accuracy in the available lime determination. Those industries who currently
do not add sugar in the test for available lime, and who have processes that
can be significantly affected by fluctuations in the available lime
determinations, may want to consider the addition of sugar to their testing
procedure. Both ASTM and AWWA provide very detailed procedures and equipment
requirements for testing both quicklime and hydrated lime. Please contact
them directly for their industry recognized and accepted standard test
procedures: (ASTM C25 - AWWA B202.)

When I obtain a sample of quicklime from a truck or railcar for
testing for the percent of available lime (CaO%) do I need to seal the
container?

Yes, it's very important to place the quicklime sample in a sealed container.
Quicklime is highly reactive with water and, when exposed to air that has
moisture in it, will undergo air slaking, which means that the quicklime
(calcium oxide)is reacting with moisture in the air to form hydrated lime.
Any portion of the quicklime sample that has reacted with moisture in the air
(water) will be converted to hydrated lime, which has a weight that is 1.32
times as heavy as it was as quicklime. The overall weight of the sample will
be increased, which will tend to reduce the available lime percent
determination. The degree to which the sample is affected is a result of the
moisture in the air. To avoid the possibility of the sample being affected by
air slaking, the sample should be sealed until it is to be tested.

When obtaining a sample of hydrated lime the sample should also be sealed,
primarily to keep the sample clean and free of debris. The hydrated lime
does not react with moisture in the air since it has already been converted
from quicklime to hydrated lime. Over an extended period of time, however,
the hydrated lime (calcium hydroxide) will react with carbon dioxide in the
air to form calcium carbonate. As a general rule then, all lime samples,
whether quicklime or hydrated lime, should be in sealed containers.

What are the CAS numbers for quicklime and hydrated lime, and what
does CAS mean?

The CAS number for quicklime is 1305-78-8 and the
number for hydrated lime is 1305-62-0. A CAS
number refers to Chemical
Abstracts Service Registry Number and
identifies a chemical. For example, the same CAS number would be used for
quicklime and calcium oxide, since they are the same compound. The CAS
number, however, tells nothing about the concentration of the chemical.
(The Chemical Abstracts Service is a division of the American
Chemical Society.)

To understand this it's important to keep in mind that then when quicklime
(CaO) reacts with water it forms hydrated lime (calcium hydroxide) which is
only slightly soluble in water. (0.159 grams per 100 grams of saturated
solution at 25o C.) A "pebble" of quicklime, when exposed to
water, will readily react and break apart due to the swelling that occurs
as a result of the larger sized crystals of calcium hydroxide that are
formed. As this occurs, more water enters the pebble, producing more
hydrated lime, and so on. If the quicklime "pebble" is in the presence of
too much water a phenomenon known as "drowning" can occur.

What happens is that, although the quicklime (calcium oxide) on the surface
of the pebble converts to calcium hydroxide (hydrated lime), the excess
water can absorb the heat generated in the reaction and result in a delay
in the hydration process. In addition, the calcium hydroxide on the
surface, because of it's limited solubility in water, will tend to block
the exposure of additional water to the quicklime within the pebble,
resulting in a delay or cessation of the hydration reaction. Quite often,
the "drowned" quicklime will be removed from the slaker as "grit", which
will later undergo hydration in the grit pile. To avoid "drowning the
quicklime" it is important to operate the slaker at both the correct water
to lime ratio, and at the optimum water temperature. A lime user who notices
an increase in the amount of grit, which appears to react later in the grit
pile, may find that they're experiencing the phenomenon of "drowning" the
quicklime.

What are the STCC, CAS and EPA reference numbers for quicklime
(Calcium Oxide-CaO) and hydrated lime (Calcium
Hydroxide-Ca(OH)2)?

All of these numbers are needed at one time or another. The STCC refers
to Standard Transportation Commodity Code, the CAS refers to
Chemical Abstract Service and the EPA refers to the
Environmental Protection Agency. For your reference the numbers
are as follows:

Reference

Quicklime

Hydrated Lime

STCC

32-741-10

32-741-11

CAS#

1305-78-8

1305-62-0

EPA#

A350-2789

S349-3522

Chemical Name

calcium oxide

calcium hydroxide

Formula

CaO

Ca(OH)2

Molecular Wgt

56.08

74.09

Mol. Wgt. Ratio

1

1.32

Note: Included in the table above are the molecular weights for both
quicklime and hydrated lime. Hydrated lime is produced from quicklime by a
reaction with water. Using the molecular weights as a ratio, 56.08 tons of
calcium oxide will react with 18.01 tons of water (molecular weight) to
produce 74.09 tons of hydrated lime. The ratio of calcium oxide to calcium
hydroxide is 1:1.32, so a truck of quicklime is equivalent to 1.32 trucks
of hydrated lime. This information is useful in determining the cost
benefits of quicklime vs. hydrated lime, and whether the savings warrant
going to quicklime.

I have completed the available lime test for CaO% and am concerned about a low
test percentage. How can I tell if my quicklime sample has undergone air
slaking?

When a quicklime sample is taken from a truck or railcar it's important that
the sample be obtained from beneath the surface. Quicklime is very reactive
with water and will readily react with moisture in the air. Depending on how
long the top hatches were open during the loading process, as well as the
humidity, the surface of the quicklime will become air slaked, or converted to
calcium hydroxide from moisture in the air. The amount of quicklime that air
slakes is very minimal compared to the total amount of quicklime in the truck
or railcar, however, if a sample of quicklime is taken from the top surface,
then the amount of air slaked quicklime could be high relative to the sample
size.

An unusually Low CaO% may indicate air slaking: A theoretically pure
quicklime, CaO (56 lbs.) will react with water H2O (18 lbs.) to
produce calcium hydroxide, Ca(OH)2 (74 lbs.). If the sample were
absolutely pure quicklime, then the available CaO% would be 100%. If the same
sample were to be completely air slaked, then the available lime would ideally
be 75.7% (56/74). Percent readings near this range can be an indication that
the sample may have become air slaked. A sample taken should be sealed, and
tested relatively soon to avoid issues of air slaking. Also, once a sample
is pulverized for testing, the sample is very prone to air slaking so the
weighing of the sample should be completed quickly to avoid air slaking. Air
slaking adds weight (water chemically reacts with quicklime) to the sample,
and steadily causes a reduction in the available lime CaO% values.

If the available lime percent readings are unusually out of line with what you
normally receive a re-test is advised. To be sure the sample is not the issue
you will want to obtain another sample from the truck or railcar, underneath the
surface, otherwise you find that you are just be re-testing a compromised
sample. Also, it's important to be certain that the acid used in the titration
is correct. Because these are prepared locally, it's important to make sure
that an error has not occurred.

What is the correlation between the Available CaO% in Quicklime, CaO and the
CaO% Equivalent in Hydrated Lime, Ca(OH)2?

The term Available Lime refers to the percent of CaO in a sample that is
available as CaO. Because quicklime is produced from the heating of calcium
carbonate that occurs in nature, it will have some impurities that are
dictated by the nature of the geological deposit. Also, in the process of producing
quicklime there will always be some calcium carbonate core due to having to
heat irregularly shaped and varying sized rocks of limestone. In some chemical
testing of lime the CaO in the calcium carbonate core is included and is
referred to as the Total CaO. This percentage is generally higher than
the Available CaO since it includes the CaO that is chemically bonded in
the calcium carbonate core.

The "Rapid Sugar Test" for available lime, either the ASTM C-25 or AWWA B202
version, is usually the chemical test that is used to determine the available
lime in a sample of quicklime or hydrated lime. In a theoretically
pure sample of quicklime, devoid of all naturally occurring impurities, and
with an unrestricted time period to convert the limestone to quicklime with
heat, you would have an ideal available lime of 100%. The available lime
percentages generally experienced in the commercial market for high calcium
quicklime typically require a minimum of either 90% or 92%, depending on the
industry. Most lime companies have available lime values higher than 92%.

In the reaction to convert quicklime to hydrated lime;
CaO + H2O --> Ca(OH)2
you are essentially doing the equivalent of taking 56.08 lbs of CaO
(mw-molecular weight) and 18.00 lbs of water (mw), and reacting them to
produce 74.08 lbs. (mw) of calcium hydroxide. Based upon the purity of
the sample, an approximate comparison can be made between the available CaO%
of the quicklime and the expected CaO% equivalent in the hydrated lime. It
can be seen from the chart below that the highest CaO equivalent possible in
a 100% pure sample of calcium hydroxide would be 75.7%.

Quicklime Available CaO% vs CaO Equivalent in Hydrated Lime

QuicklimeAvail. CaO%

Hydrated Lime,CaO Equiv.

QuicklimeAvail. CaO%

Hydrated Lime,CaO Equiv.

100%

75.7%

92%

69.6%

99%

74.9%

91%

68.9%

98%

74.2%

90%

68.1%

97%

73.4%

89%

67.4%

96%

72.7%

88%

66.6%

95%

71.9%

87%

65.8%

94%

71.1%

86%

65.1%

93%

70.4%

85%

64.3%

Is using this table it's important to keep in mind that the process of
hydration is not perfect, so that some loss of available CaO% can occur.
Because of this the table should be viewed only as a general guideline.

As I understand it, hydrated lime is only slightly soluble in water and the
solubility is inversely proportional with temperature. What is the actual
solubility of hydrated lime in water with temperature? Also, how is the
solubility of quicklime determined since quicklime reacts with water to form
hydrated lime and is not in its original form in a water solution?

Although hydrated lime is only slightly soluble in water, as can be seen in
the chart below, the effectiveness of the solubility is increased by
the suspension in water of the very small particles of hydrated lime that were
formed during the hydration process. This suspension (slurry) of lime
dramatically increases the dissolving process. Also, the solubility of lime
in water is inversely proportional with temperature. The chart below shows this
temperature/solubility relationship and it's apparent that the highest
solubility of lime is at the freezing point of water and the lowest is at
the boiling point water.

Solubility of Lime in Water

Saturated Solution - grams per 100 gms of solution

ToC

Ca(OH)2

CaO

ToC

Ca(OH)2

CaO

0

0.185

0.140

50

0.128

0.097

10

0.176

0.133

60

0.116

0.088

20

0.165

0.125

70

0.104

0.079

25

0.159

0.120

80

0.092

0.070

30

0.153

0.116

90

0.081

0.061

40

0.140

0.106

100

0.071

0.054

Determination of Solubility of Quicklime in Water:
Since quicklime calcium oxide (CaO) cannot exist in water in the oxide form,
the solubility of CaO in water is based on the calcium oxide equivalent
of CaO in Ca(OH)2. The values for the solubility of CaO in water,
shown in the chart above, represent the amount of CaO that is within the
dissolved Ca(OH)2. The calculation for the ratio of CaO in
Ca(OH)2 appears below:

Since magnesium carbonate is chemically very similar to calcium carbonate
why doesn't magnesium oxide and magnesium hydroxide have the exact same
chemical properties as calcium oxide (Quicklime) and calcium hydroxide
(Hydrated Lime)?

Magnesium appears above calcium on the Periodic Table of Elements
(see below) and has an atomic number of 12 and a molecular weight of 24.32,
whereas calcium has an atomic number of 20 and a molecular weight of 40.08.
Both have a charge of +2 as an ion after two electrons have been removed from
their s-orbits. This is the maximum number of electrons that can be removed
from their s-orbital, which can hold can hold only two electrons, so both
undergo similar reactions with other elements and chemical groups. Even though
the charge appears to be identical, the "effective charge" is somewhat
different and accounts for the difference in reactivity, as is described in
the following paragraphs.(For additional on the energy levels, sublevels and
orbitals of atoms see the Chemistry Reference Note section that appears just below the partial Periodic Table of Elements
at the end of this section.)

There are two factors that come into play with regard to
the "effective charge" of the Ca+2 and Mg+2 ions:

(1) Although both calcium and magnesium ions have a +2 charge, the distance
from the ionic extremity (border) to the +2 charge at the nucleus is different.
In the case of magnesium, the size (radius) of the ion is smaller (0.66 Anstrom
units) than that of calcium (0.99 Anstrom units). The increase in the size of
the calcium ion is due to the addition of another energy level. Consequently,
the distance from the +2 charge to the extremity of the ion in the magnesium
ion is shorter by about 33% then the distance in calcium. The shorter distance
means that the electrostatic attraction between the magnesium ion (+2) and the
oxygen ion (-2) is stronger than that of the bond between the calcium ion (+2)
and the oxygen ion (-2). Note that, in both cases, the +2 charge offsets the -2
charge and results in the neutral compounds of CaO and MgO. However, the
inherent elemental differences (number of protons and electrons) between
the elements of calcium and magnesium, result in a difference in their ease of
ionization (removal of electrons) and their ability to chemically
combine (strength of their electrostatic forces) with other elements
and compounds in reactions.

(2) Also, in the case of the calcium ion, even though the charge is the same as
that of magnesium, the +2 charge at the nucleus of the calcium ion has to go
through more electrons, eighteen (-18), compared to the magnesium ion which has
a +2 charge, but only has to go through ten (-10) electrons. This reduces the
overall attraction (strength) that the calcium ion (+2) has for other elements
and chemical groups as compared to magnesium.

Effects on Solubility: Because of this effectively "weaker" +2 charge,
the solubility of calcium hydroxide is greater than magnesium hydroxide. The
water molecules clustering around the calcium hydroxide compound have enough
force (Van der Waals force) to dissociate the compound into a calcium (+2) ion
and two hydroxyl (-1) ions, although not to a great degree, which accounts for
the limited solubility of calcium hydroxide in water. In the case of magnesium
hydroxide, the attraction of the magnesium +2 ion and the hydroxyl -1 ion is
too great for the water molecules to overcome, and the magnesium hydroxide
remains mostly out of solution.

The difference between calcium and magnesium can be readily seen on the
Periodic Table of Elements. Although calcium is just below magnesium
vertically, there are six elements between them horizontally. Nature does
favor calcium carbonate and magnesium carbonate occurring together, so even
deposits of high calcium limestone will have some magnesium carbonate mixed
in, which is considered a "naturally occuring impurity."

For comparative purposes, Mg(OH)2 has a solubility of 0.0042 grams
per saturated solution, which can be considered insoluble in water.
Furthermore, the reaction of MgO with water is not highly exothermic, so MgO
will stay in water as "grit". CaO, however, will quickly convert to the
hydrated lime form in a dramatic exothermic reaction. MgO can be forced to
react more quickly with increased pressures and temperatures. For reference,
a partial Periodic Table of Elements appears below:

Periodic Table of Elements (Partial)Elements 1-109

1

1H1.008

2He4.08

2

3Li 6.94

4Be 9.01

5 B10.81

6 C12.01

7 N14.01

8 O16.00

9 F19.00

10Ne20.18

3

11Na22.99

12Mg24.31

13Al26.98

14Si28.09

15 P30.97

16 S32.06

17Cl35.45

18Ar39.95

4

19 K39.10

20Ca40.08

21Sc44.96

22Ti47.88

23 V50.94

24Cr52.00

25Mn54.94

26Fe55.85

27Co58.93

28Ni58.69

29Cu63.55

30Zn65.38

31Ga69.72

32Ge72.59

33As74.92

34Se78.96

35Br79.90

36Kr83.80

5

37Rb85.5

38Sr87.6

39Y 88.9

40Zr91.2

41Nb92.9

42Mo95.9

43Tc(99)

44Ru101.0

45Rh103.0

46Pd106.4

47Ag107.9

48Cd112.4

49In114.8

50Sn118.7

51Sb121.8

52Te127.6

53I 126.9

54Xe131.3

6

55Cs132.9

56Ba137.3

57*La138.9

72Hf178.5

73Ta180.9

74W 183.9

75Re186.2

76Os190.2

77Ir192.2

78Pt195.1

79Au197.0

80Hg200.6

81Ti204.4

82Pb207.2

83Bi209.9

84Po(209)

85At(210)

86Rn(222)

7

87 Fr(223)

88 Ra(226)

89+ Ac(227)

104Rf(261)

105 Ha(262)

106 Sg(263)

107 Ns(262)

108 Hs(265)

109 Mt(267)

The Lanthanide and Actinide Series are shown below:

Lanthanide Series*

58Ce140.1

59Pr140.9

60Nd144.2

61Pm(145)

62Sm150.4

63Eu152.0

64Gd157.3

65Tb158.9

66Dy162.5

67Ho164.9

68Er167.3

69Tm168.9

70Yb173.0

71Lu175.0

Actinide Series+

90 Th232.0

91 Pa231.0

92 U 238.0

93 Np237.0

94 Pu(244)

95 Am(243)

96 Cm(247)

97 Bk(247)

98 Cf(251)

99 Es(254)

100 Fm(257)

101 Md(258)

102 No(259)

103 Lr(260)

Element

Reference

At 25oC

Atomic No.ElementSymbolAtomic Wgt.

Alkali Metals

Alkaline-Earth Metals

Transition Metals

Post Transition Metals

Metalloids

Nonmetals

Holgens

Noble Gases

Solid Gas Liquid

For comparative purposes, Mg(OH)2 has a solubility of 0.0042 grams
per saturated solution, which can be considered insoluble in water.
Furthermore, the reaction of MgO with water is not highly exothermic, so MgO
will stay in water as "grit". CaO, however, will quickly convert to the
hydrated lime form in a dramatic exothermic reaction. MgO can be forced to
react more quickly with increased pressures and temperatures.

Chemistry Reference Note

PRINCIPLE ENERGY LEVELS, SUBLEVELS AND ORBITALS

Calcium and Magnesium Ions:
Both calcium and magnesium have two electrons in an s-orbital. In the case
of magnesium, the two electrons are in its 3s orbital (3rd energy level, 3s
orbital). For calcium, the two electrons are in its 4s orbital (4th energy
level, 4s orbital). Only the electrons that are in the outermost Principle
Energy Level of an element are available for chemical reactions (chemical
bond formation). Electrons in energy levels lower than the outermost energy
levels have the electron configurations (energy level structures) of noble
gases, which are completely stable and do not chemically react under normal
circumstances.

Principle Energy Levels, Sublevels & Orbitals:
There are seven Principle Energy Levels which correspond to the horizontal
rows on the Periodic Table of Elements. At the end of each row is a noble gas.
The noble gases are He-Helium, Ne-Neon, Ar-Argon, Kr-Krypton, Xe-Xenon, and
Rn-Radon. (Although Radon does not react chemically, it's nucleus is unstable
so it is radioactive. It is formed by the natural breakdown of uranium in
soil, rock and water.) Within each Principle Energy Level are sublevels
designated as s,p,d,f. Within each of these sublevels are orbitals, and each
orbital can contain two electrons. Note that not all Principle Energy Levels
have all of the sublevels. The number of orbitals in each sublevel increases
from s,p, d through f. The orbitals represent a three dimensional space in
which the two electrons exist.The s sublevel has a single spherical orbital
and the p,d and f sublevels have dumbbell shaped orbitals in which each
of the two electrons occupy opposite ends of the dumbbell. This is somewhat of
an oversimplication, but it helps in visualizing orbitals. The p, d and f
orbitals are what gives structure and shape to molecules (compounds).

The order of the orbitals shown below is not necessarily the order in which they actually appear in elements due to
differences in the energies of orbitals. However,it useful to view them
in this simplified way for reference purposes.

The following Short Form of indicating electron configurations helps
to highlight why only the outermost energy level participates in chemical
reactions. Note that the inner energy levels are identical to the noble gas
electron configurations and are completely stable.

Building the Periodic Table of Elements:
The Periodic Table of Elements can be built by starting with Hydrogen and
adding one proton and electron, and continuing on through the elements. As the
elements get larger, more neutrons are required to stabilize the nucleus, which
will increase the weight of the element, however, the identity of element is
determined only by the number of protons. The neutrons are not involved with
normal chemical reactions. In viewing the Actual order of electronic
configurations, it can be seen that the s orbitals are more stable than the
d and f and will fill earlier than the d and f sublevels of lower energy levels.

What is the ASTM Standard C-977 and does the lime produced by Cheney
Lime & Cement Company meet this specification?

The ASTM C-977 is the ASTM standard specification for quicklime and hydrated
lime used in soil stabilization. The quicklime and hydrated lime produced by
Cheney Lime & Cement Company meets the specifications of Standard C-977.

Lime companies refer to a "Typical Chemical Analysis". What does this
mean and why is it not referred to as a specific chemical analysis like the
reagent grade chemicals I buy?

All industrial lime is produced from quarried limestone (or in some cases
oyster shells), which has naturally occurring impurities in it. Many
companies wash the stone before in goes into the kiln, however, any
impurities in the limestone itself will appear in the quicklime. Much of
the control of the quality of the quicklime can be affected by how well the
material is quarried. The vein of limestone being quarried is constantly
monitored to insure that only the highest purity is selected for the kiln.
The quicklime produced is chemically analyzed, based upon standard
statistical sampling procedures, but the chemical analysis will vary to a
degree according to the way nature left the limestone deposit. This is why
most companies refer to a "typical chemical analysis." There are minimum
and maximum chemical limits to the various components of the lime, but
within these limitations the chemical analysis will always vary to some
degree. (Note: Lime can be produced from oyster shells, which have a very
high purity of calcium carbonate, however, this source of kiln material is
declining, having been almost completely replaced by quarried
limestone.)

With regard to the NAFTA Certificate of Origin, what does the HS Tariff
Classification Number mean and what are the HS Tariff Classification
Numbers for quicklime and and hydrated lime? Also, what does the
Preference Criterion mean?

The "HS" in HS Tariff Classification Number refers to "Harmonized System"
which is short for Harmonized Commodity Description and
Coding System.
This is a system for classifying goods in international trade. In the case of
quicklime the number is 2522.10 ("calcium oxide, obtained from the product
of calcining natural materials"), and for hydrated lime/slaked lime)
it's 2522.20 ("calcium hydroxide obtained from the product of calcining
natural materials"). For calcium oxide and calcium hydroxide that is not
obtained from calcining natural materials, the HS code is the same for both
products; 2825.90. ("calcium oxide and hydrated lime in the pure state").
The 2825.90 products can be considered to be "reagent-grade" lime products rather
than "commercial-grade" lime products. Reading
the HS number: (Example: quicklime 2522.10) The first two digits are the
chapter 2522.10, the third and fourth digits
2522.10 are the header, and the fifth and sixth digits
2522.10 are the sub header.

The Preference Criterion refers to a code designating the
degree to which the products are coming from the country of origin. In the
case of quicklime and hydrated lime from Cheney Lime & Cement Company, all of
the components are USA based, so the designation would be "C". More specifically,
from the NAFTA Certificate of Origin Instructions, a Preference Criteria "C"
refers to "The good is produced entirely in the territory of one or more of
the NAFTA countries exclusively from originating materials."

Slaked Lime: In the description of calcium hydroxide products in the HS Tariff
Classification System, it can be a bit confusing. In one instance it will
refer to calcium hydroxide as "hydrated lime", then another time as "slaked lime".
Hydrated lime produced from calcined limestone (quicklime) can be thought of as
simply a reaction of the quicklime (calcium oxide, CaO) with the exact amount
of water (H20) to produce a dry hydrated lime (calcium hydroxide,
Ca(OH)2). The term "slaked lime" refers to the reaction of quicklime
with water to a dry powder, as well as the addition of excess water to produce
a paste, slurry or milk of lime. Technically then, dry
hydrated lime is also considered to be slaked lime.

What is the difference between the temperature scales of Celsius/Centigrade
(oC), Fahrenheit (oF) and Kelvin (oK)
and how do I convert between these?

Kelvin & Celsius

Celsius & Fahrenheit

K = C + 273

C = 5/9 x (F - 32)

C = (0.556 x F) - 32

C = K - 273

F = (9/5 x C) + 32

F = (1.8 x C) + 32

Fahrenheit - The Fahrenheit temperature scale is
based upon 32 oF as the freezing point of water and
212 oF as the boiling point of water. (The Fahrenheit scale was
devised by Gabriel Daniel Fahrenheit (1686-1736), a natural philosopher who
invented the mercury thermometer in 1714.)

Celsius (Centigrade) - The Celsius (Centigrade)
temperature scale is based upon 0 oC as the freezing point of water
and 100 oC as the boiling point of water. The formulas to convert
between Fahrenheit and Celsius (Centigrade) come from the fact that there are
180 degrees (212-32) between freezing and boiling in the Fahrenheit temperature
scale, so each degree in the Fahrenheit scale is equal to 100/180 (or 5/9)
of the Celsius/Centigrade scale. (The Celsius scale was devised in 1742 by
Anders Celsius (1701-1744), a Swedish professor of astronomy.)

Kelvin - The Kelvin temperature scale is based upon
the physics of cooling a gas and represents an extrapolation of the Centigrade
temperature scale to -273 oC (or more accurately, -273.15
oC) at which point there is no longer any motion of atoms or
molecules; or put in the simplest way, "there is no heat". This point in the
Kelvin temperature scale is assigned a value of 0oK. For the
Celsius (Centigrade) temperature scale the freezing point of water would be
273oK and the boiling point would be 373oK. (The Kelvin
temperature scale was developed by Lord Kelvin (1824-1907), a British physicist.)

When in contact with metal equipment does lime have any affect on iron or
steel? Also, is there any affect on aluminum, lead, tin, brass or zinc?

Without water (H2O) being present, neither
quicklime (CaO, calcium oxide) nor
hydrated lime
(Ca(OH)2, calcium hydroxide) react with metals.
If water and quicklime are both present the water will first react with
the calcium oxide, converting it to calcium hydroxide (hydrated lime). When
water is present in excess of the amount required to convert quicklime (CaO)
to hydrated lime, or the hydrated lime is moist or in a slurry, it is
in a form that can attack metals. Lime (quicklime or hydrated) doesnot
react with (attack) either iron or steel. However, lime does
react with (attack) aluminum, lead, brass and zinc. Since lime does
not attack iron and steel these metals are generally used for lime handling
equipment.

Since the pneumatic trucks hauling lime (calcium oxide or calcium hydroxide)
are made of aluminum alloy, the lime does not have the same capacity to attack
the metal as it would if they were made of aluminum. In addition, quicklime
acts as a desiccant in that it will react with any moisture in the tank
preventing the lime from going into solution. In the case of calcium
hydroxide, any moderate amount of water will be electrostatically attracted to
the hydrated lime, which will also help prevent a solution of any sort forming.
One of the best sources for information on the effect of lime on metals comes
from Robert S. Boynton's book the "Chemistry and Technology of Lime and
Limestone", 2nd edition, 1980, page 223, where he states the following:

"Effect on Metals. When in contact with metal
equipment, lime does not affect steel or cast iron to the slightest extend. In
fact, by coating these metals with a lime whitewash, it acts as a conservation
agent by protecting the metals from oxidation. However, any form of lime or
strong alkaline will disastrously attack and destroy aluminum, except
special alkaline resistant alloys of this metal. Lead and and
brass are also readily attacked, and under some circumstances lime
will literally dissolve lead."

I understand that limestone (calcium carbonate and/or magnesium carbonate can
be used to neutralize a strong acid. Why can't I simply use limestone to raise
the pH above 7.0 (neutral)?

A strong acid, such as hydrochloric acid (HCl), can react directly with various
forms of limestone,
(CaCO3, MgCO3 or CaCO3MgCO3).
For example, the reaction of CaCO3 with HCl is:
CaCO3 + 2HCl --> CaCl2 + H2CO3.
The carbonic acid produced is unstable and breaks down into carbon dioxide (gas)
and water: H2CO3 -> CO2 + H2O.
However, CO2 is soluble in water and produces a weak carbonic acid,
so you ultimately find that the neutralization of a strong acid with limestone
results in the generation of a weak acid. Consequently, you can never reach
a point above a pH of 7.0.

Note: Carbon dioxide (CO2) which is a component of the atmosphere
will combine with rainwater to produce carbonic acid, H2CO3,
which can dissolve limestone over time. Also, sulfur dioxide (SO2)
in the air can also dissolve in the water, which produces a strong acidic
solution of H2SO4 (sulfuric acid). This result of this
process is referred to as acid rain.

What is the weight in lbs. of one U.S. gallon of hydrated lime? Quicklime?

The quickest and simplest way to determine this would be to fill a gallon jug with hydrated lime currently being used,
weigh it and deduct the weight of the gallon container. Because of the nature of hydrated lime, however, the actual
weight can vary quite a bit depending on how packed it becomes, especially in transit. For reference, a weight range
and average for hydrated lime (and quicklime) can be calculated from the follow conversion formula:
1 US gallon = 0.133680556 cubic feet .

Hydrated Lime (Average 4.68 lbs/gallon): The density of hydrated lime is approximately 30 to 40 lbs per
cubic feet depending on how packed the hydrated lime is. Using the formula above the weight would range from 4.01 to
5.35 lbs per gallon, or an average of 4.68 lbs per gallon.

Quicklime (Average 7.69 lbs/gallon): The density of quicklime is approximately 55 to 60 lbs per cubic feet,
depending on how packed the quicklime is, so
the corresponding calculations for the weight of a U.S. gallon of quicklime would be 7.35 to 8.02 lbs per U.S. gallon,
or an average of 7.69 lbs per U.S. gallon. Since quicklime is sold is varying sizes (pebble, granular, pulverized,
etc.) this should be considered a rough approximation. As in the case of hydrated lime, the best way to determine this
is to weigh a gallon of the quicklime currently being used.

What is the best way to dissolve hydrated lime (calcium hydroxide)?
Cold water? Mild or weak acids? Or something else?"

The first thing to be aware of is that the solubility of calcium hydroxide in water is an
inverse relation with temperature. The data below shows this relationship as
"Solubility of lime expressed as Ca(OH)2 at different temperatures
g/100 g saturated solution":

For those not familiar with solubilities here are some common examples:
(1) Salt, NaCl, is quite soluble in water and has a solubility of 36.09 grams at
20oC.
(2) Sugar/Sucrose, (C12H22O11), has a
solubility of 201.9 grams at 20oC.

Cold Water - Although the solubility of calcium
hydroxide in cold water is over twice that of boiling water, both solubilities
are still very low. Depending upon your requirements of calcium hydroxide is
solution, cold water will give you the highest solubility. It's also very
important the hydrated lime be in a "milk of lime" suspension. This is
accomplished by continually stirring the water/sample and can be achieved
because of the small particle size of the hydrated lime which dramatically
increases the surface area of the lime, subsequently increasing the effective
solubility of lime.

Strong Acid - Ca(OH)2 is a strong base.
Using a strong acid, such as HCl or H2SO4, present
different scenarios. With hydrochloric acid, HCl you would have the reaction of
Ca(OH)2 + HCl -> CaCl2 + 2H2O, which would
effectively "dissolve" the lime by forming the soluble salt calcium chloride.
If you used sulfuric acid, H2SO4 you would produce the
precipitate CaSO4 (gypsum) which would be simply switching one
solid (calcium hydroxide) for another (calcium sulfate). The real issue is
that the Ca(OH)2 is not "dissolved", but rather reacted. If this
is your objective you would have to take into account the nature of the salt
produced (dissolved or as a precipitate, etc.)

Weak Acid- A weak acid presents a situation where,
unless the lime were to be stochiometrically equal to the acid, all of the
calcium hydroxide would not be reacted, nor dissolved in the water, and would
then be available to act as a buffer. After neutralizing the weak acid, the
remaining calcium hydroxide would react with any additional acid introduced
into the solution.

Something Else - An alternative to using an acid
would be to add sugar. This forms an intermediate product (calcium sucrate)
and effectively increasing the solubility of calcium hydroxide in water by
about 90 times. (This is why sugar is added to the sample solution before
titrating the lime sample for purity. The test procedures are described
in another part of our FAQ's.)

Production Process - In the process of making
hydrated lime we first dissociate CaCO3 in kilns into CaO and
CO2 (which leaves as a gas), then react the CaO with water to
produce the calcium hydroxide. The reason it's important to keep this in mind
is that the crystal structure of CaCO3 and CaO are similar, whereas,
Ca(OH)2 is quite different. Because of this, in the reaction
process the CaO is fractured at the atomic level, producing extremely fine
particles of Ca(OH)2. The reason this is so important to your
question is due to the very low solubility of calcium hydroxide in water. That
solubility relationship is inverse with temperature (as shown in the previous
question above, No. 20).

Dissolution Process - With regard to the dissolution
process, and accounting for the low solubility is water, I have not found a
definitive answer. Most people assume that the solubility of a solid in water
increases with temperature, however, although this generally holds true,
there are a number exceptions. For example, lime is inversely proportional
with temperature, as in cesium sulfate,
Ce2(SO4)3. Sodium chloride, NaCl, contrary to
popular belief, is only slightly more soluble in boiling water than cold water,
whereas, potassium nitrate's (KNO3) solubility dramatically increases with
temperature.

My General Opinion - In the case of calcium
hydroxide, and calcium oxide (which converts immediately to calcium hydroxide
when exposed to water), it is likely that the orientation (polarity) of
the molecule, and the bonding forces that come into play, both help to result
in a low solubility to start with. The Ca-OH bond has to be overcome the water
molecules, to separate the ions in solution, which is what happens as lime
dissolves. Both Ca+2 and OH-1 are the ions in solution
and the charges are balanced by the polar nature of water*.
The overall structure of Ca(OH)2 does not appear polar enough to
allow it to be dissolved as a molecule, so any remaining calcium hydroxide
remains as a solid. The inverse relationship of solubility with temperature is
likely the result of the dissolution of lime in water being slightly
exothermic, so any increase in temperature would reverse this "reaction".
(I welcome any comments, or corrections to this opinion.)

*POLAR NATURE OF WATER

Sodium chloride (salt) offers a simple example of the solubility of a substance
in water. Although sodium chloride (NaCl) dissolved in water is often
depicted as if the ions are "floating" around separately as Na+
and Cl-, the ions actually exist as the Na+ surrounded
by a large number of water molecules with the O (oxygen) portion of the water
molecules clustered around the Na+ ion. The same is true for the
Cl- ion except that it's the H (hydrogen) portion of the water
molecules that are towards the Cl- ion.

Water is a "polar molecule" because of it's shape, as is shown to the right.
The angle formed by the H-O-H is 104.45o This gives the water
molecule a partial negative (-) charge on the oxygen side and a partial
positive (+) charge on the side where the hydrogen atoms are. These partial
charges are the result of the oxygen having a higher electronegativity
(attraction) toward the electrons then hydrogen, so the electrons spend more
time towards the oxygen atom. Even though the water molecule is electrically
neutral, from a molecule standpoint, there are partial positive and negative
charges due to the electron not being evenly distributed around the molecule,
and resulting in partial charges toward opposite ends of the water molecule.
If the water molecule were in a straight line, H-O-H, it would not be a polar
molecule and the physical characteristics of water would be different.

We are going to build a plant that will use quicklime and need to know
which is the best quicklime size to use in the design of our plant.

Quicklime Sizes: In the lime market that Cheney
Lime & Cement Company serves, quicklime generally falls into one of the
following two size classifications: Pebble Quicklime and Granular
Quicklime. Although lime suppliers have various gradations of these
two classifications it is helpful to view pebble quicklime as a size that
generally ranges from about 1 to 1/4 inch, and granular quicklime from
about 1/4 inch down. For the most part, the size quicklime that dominates
the market is pebble quicklime, and granular quicklime can be considered as
available in relatively limited supply. Most lime companies further divide
the pebble quicklime sizes into sub categories: medium and
rice quicklime. Although there are slight differences in the
specific sizes between suppliers, you can consider the medium size to
generally be from about 1 to 1/2 inch, and the rice size from about 1/2 to
1/4 inch. (Individual lime producers can tell you their specific size
ranges.)

Best Quicklime Size: In some situations the
size is very clearly defined and the plant designer has no option. Usually
this involves the major classifications of pebble and
granular quicklime. However, within the sizes of medium and
rice size pebble quicklime, the plant designer has options to
consider. From a product availability standpoint the best design choice is
to make certain that the plant can run either medium or rice quicklime, and
if possible also granular. This is especially important if there is a high
demand for quicklime, whether on a continuous or emergency basis. The
following paragraph explains this further.

Product Availability Factor: The cost of
quicklime is very freight intensive, so quicklime is usually considered a
regional product. Because of this all of the quicklime used at a specific
plant comes from a relatively close geographical area. Whether that area
has one producer, or multiple producers, all of the quicklime has to be
processed through kilns. In most lime production areas there are often
multiple kilns in production. During processing, the quicklime is crushed
and screened to generate the various sizes. If the available pebble
quicklime sizes in an area were evenly split between medium and rice, and
your plant can only use medium, your available supply of quicklime from
producers would only be half of what is actually produced. If you require
a granular size quicklime the situation becomes even more difficult since
this is considered to be a minor size in the lime market.

Recommendation: It is recommended that a new
plant be designed to at least be able to run either medium or rice. The
plant may not be able to alternate between truckloads of the medium and
rice sizes, but in the event of a lime shortage, the plant would be able to
switch sizes. It is not recommended that a granular size be used for a
high volume user, unless this size is mandatory for the process, since this
could severely limit product availability, especially during peak demand
periods.

When I buy quicklime from different suppliers I sometimes have to
adjust my system, even though the size of the quicklime is the same. Why
are there variations in quicklime from different suppliers?

Although the high calcium quicklime received from different lime suppliers
is essentially the same chemical (calcium oxide), each deposit of limestone
from which the quicklime is produced has naturally occurring impurities.
These can vary between suppliers because of different geological deposits,
as well as from different parts of the same quarry of a single company.
Because of this, there are inherent differences between the quicklime from
various lime suppliers. Also, both the kiln operating characteristics and
the type of fuel mixture used can be a factor. If each lime supplier uses
a slightly different mixture of fuel (i.e. pet coke and pulverized coal)
the effect on the quicklime produced can vary slightly. In addition, there
are different types of kilns used in the production of quicklime, each of
which can produce a quicklime with slight differences. Most users of
quicklime in the market will not be aware of any of these slight
differences, however, occasionally there is a lime user who finds that
their lime system is sensitive to these. From a marketing standpoint, it
is in a lime user's best interest to design their lime system to be able to
use any good quality high calcium quicklime, without regard to the factors
of quarry source, kiln type, etc., since this will prevent them being
limited to only one supplier, or to one particular plant or kiln within a
specific company.

With regard to deliveries by truck or rail, how large a lime silo
should we plan for in the design of our plant?

As would be expected, the lime silo capacity is greatly affected by the
specific needs of a company which will need to be taken into account, along
with the daily lime demands. From a transportation delivery standpoint
there are some things that can be useful to keep in mind. (Please be aware
that the suggestions for silo capacities shown in the following paragraphs
are approximate and are provided only to help you get an idea of the
requirements for lime delivery by truck and rail, and to see the
differences between the two. Each plant design has its own unique
requirements which should be carefully considered before the investment in
storage capacity is undertaken.)

Truck Delivery: A truck can generally be
considered to hold about 25-30 tons of quicklime. The minimum freight
weight requirements are usually 25 tons for quicklime (50,000 lbs) and 22
tons for bulk hydrated lime (44,000 lbs); bulk hydrated lime is lighter
than quicklime. A weight of 25 tons/truck is useful to use as a general
guideline since it will cover most shipments. Generally, you are
allowed one to two hours for unloading a truck before a demurrage charge is
applied, based upon the individual carrier's policy. Depending upon your
demand for lime, any silo you design should be able to hold no less than
2 trucks of lime (50 tons). If a truck is ordered when the silo gets
to the point where it can hold a full truck, you avoid problems associated
with demurrage. This is quite a small silo, so it is recommended that,
dependent upon your requirements, you have a silo that can hold 4-5 trucks
(100-125 tons) of lime. The additional silo capacity will give you an added
buffer in the event of unforeseen truck delivery problems.

Rail Delivery: A railcar can generally be
considered to hold about 100 tons of lime. In our market area bulk hydrated
lime is usually not shipped in rail cars aside from PD cars (Pressure
Differential cars), which are owned by the lime user or lime supplier.
Usually the railroad will allow
you two days to unload a railcar. Depending upon your demand for lime, the
silo should be able to hold no less than 1-1/2 rail cars of lime (150
tons). Rail delivery times are not as specific as truck, so it's important
to consider having additional silo capacity. A silo with 250 tons will
enable you to unload two cars into a silo when less than 50 tons are
remaining in the silo. Although your lime demands may dictate your silo
requirements, a silo with 500 tons capacity would enable you to have an
added buffer for unforeseen rail delivery problems. (i.e. a rail car
enroute is set aside for a day to be repaired, etc.)

I am in the final planning stages for our lime silo and want to make sure
that I've have covered all key points. Is there something I need to be
sure to check before ordering the silo?

The answer to this is yes. It's very important that the silo have enough
product capacity. Quite often a silo is designed to hold only one truckload of
lime. This presents a problem because the lime user has to wait until
they're almost out of lime to order so that they can fit all of the lime
into the silo. A lime company generally processes an order as "a truckload
of lime". Dependent upon whether it's quicklime or hydrated lime, the
weight will vary due to the density of the lime and/or the capacity of the
pneumatic truck. In any case, it's a wise decision for the lime user to
have additional capacity available in the silo so that a truck can be
ordered and received without having to have the silo completely empty.

One other very important point to be careful of involves the density used
in the calculation of silo size. The term "lime" refers to both
quicklime/calcium oxide and hydrated lime/calcium hydroxide, however the
density of the two materials are significantly different. Generally,
quicklime is shipped as "pebble quicklime" whereas hydrated lime is a fine,
white powder similar in consistency to "flour". It's important to be sure
to know exactly which product will be going into the silo. Some lime users
have used the density of quicklime in their calculations when they were
actually going to be using bulk hydrated lime. The result is a silo which
will not hold a full truck of hydrated lime.

I need to remove some lime that is currently in my silo. Does anyone
do this and what are the type of charges that I can expect?

Unless it's not possible, the least expensive way to remove the lime from
the silo is to run it through the system, even if this has to be done at a
slower pace. If it's determined that the lime must be removed from the silo
there are companies who have trucks called self loading vacuum
trucks which can vacuum out the dry product and then take it to another
location. To accomplish this a fitting (approximately 4") has to be placed on the
opening at the bottom of the silo so that the truck's vacuum system can be
attached. Some of the charges associated with this type of operation are:

Charge per mile to and from the site of the silo.

Charge to clean the truck before and after handling the lime.

Cost per hour for the actual operation.

Here are three companies we are aware of that can provide this type of
service:

Marion Environmental Services, Chattanooga, TN:
423-495-4919

Bulkmatic Transport, Jacksonville, FL:
904-786-8116

Fenn-Vac,
Inc, North Charleston, SC: 843-552-8306

For pricing and availability of equipment please contact these companies
directly. If either of these companies are not able to provide this service
in your area, they should be able to direct you to a company near you.
(Other companies that can provide the service of removing dry lime
from a silo may contact us at sales@cheneylime.com. We would be pleased to
include their name and phone number here as a service to our customers and
other lime users.)

How can I do a quick calculation of the cubic feet capacity of a silo?
Also, how much quicklime, or hydrated lime, can go in the silo?

When determining the size of the silo that you require it's important to make
certain that you use the correct density for the product required. As you can
see below, the density difference between quicklime and hydrated lime is
very significant.

Example: The following calculations apply to a circular silo with a
single cone at the bottom. The cylinder part of the silo is 20 ft. high and the cone part of the silo
is 5 ft. high. The diameter of the cone is the same as the cylinder. The
diameter of the silo is 12 ft., so the radius is 6 ft. (For silos having
multiple cones, each cone would be calculated individually based upon its
diameter. The volume of all the cones would be combined with the volume of
the cylinder.)

Silo Product Capacity in Tons of Lime:
To estimate the number of tons of quicklime, or hydrated lime, that a
silo can hold simply multiply the silo volume times the average
anticipated lbs./cu. ft and divide by 2,000 lbs. Since both lime
products can vary in density, an approximate range can be used:

Approximate Densities of Limes

Pebble Quicklime =

65 to 70 lbs./cu.ft.

Hydrated Lime =

25 to 35 lbs./cu.ft.

For reference: π (called "pi") is the ratio of the
circumference to the diameter of a circle and is the same for all
circles. It is approximately equal to 3.14159... (The decimal
expansion never ends and does not repeat.)

What is a "slaker" and why can I not simply mix quicklime in a simple
mixing tank?

As a general rule "pebble quicklime" requires the use of a slaker whereas
"hydrated lime" can be mixed with a standard mixer. To understand this it
helps to visualize the pebble quicklime as identical to the original
limestone pebbles that it was created from, except that it's about 44%
lighter. (The carbon dioxide, produced during the dissociation of calcium
carbonate into calcium oxide and carbon dioxide, escapes through the
porous limestone.) When these pebbles drop into a simple mixer they go
immediately to the bottom of the container, reacting as they go. A layer of
"reacting rocks" builds up on the bottom of the tank and consumes the water
in the surrounding layer of quicklime. The result is that all of the quicklime
may not react. Un-reacted quicklime that gets into a pipe can cause problems
because of the steam emitted as it converts to the hydrated form. To avoid
this problem, a slaker is used which can be thought of as a "specialized mixer".
The quicklime pebbles encounter a screw or paddles at the bottom of the tank
which insure that all of the quicklime comes into intimate contact with the
water and completely converts to the hydrated lime. A slurry is produced,
similar to that used in a hydrated lime mixing tank, but it's essential
that all of the quicklime gets completely converted.

Why does hydrated lime settle when the agitation stops? Why doesn't
it all go into solution?

Hydrated lime (calcium hydroxide) is only slightly soluble in water. The
particle size is very small, so agitation of the solution will keep the
particles suspended until the agitation is stopped. The small size of the
particle in suspension is responsible for the reactivity of hydrated lime.
Since the particle size is so small, the surface area of the hydrated lime
exposed to water increases dramatically. As hydrated lime (calcium
hydroxide) in solution is used up in reactions, additional lime goes in
solution to replace it.

I have a slaker, or other type of lime handling equipment, that requires a
part that is no longer available or manufactured. Is there a company who
can make this part for me if I have the drawings/specifications, or if all
I have is the broken part(s)?

A company may have lime handling equipment that requires a part that is no
longer made. The equipment may still be in reasonably good shape, but the
part is not available anymore; possibly due to being obsolete, or no longer
supported by the manufacturer. A company by the name of Anthoine Machines Works, Inc. in Fort Valley, GA
(USA) can reproduce the part from drawings or from the damaged part(s). The
company was established in 1885 and has been providing this service to
companies throughout the world. Their phone number is 478-825-5613. They
should be able to help you. If it is a type of work that they are not able
to do they should be able to help direct you to someone who can help you.
(Generally stated, this company produces parts for equipment, both current
and obsolete; custom parts.)

What is a Lime Slurry and are there other physical forms of hydrated
lime and water? Also, is there a formula that can be used in calculating the
amount of lime and water to produce a certain percent slurry?

There are generally six physical states of hydrated lime that are used in
industry. Other than the dry forms, the differences involve amount of water
mixed with the hydated lime. These six forms are:

Type of Lime

Solids

Water

Dry Hydrated Lime

100%

0%

Lime Putty

70 - 55%

30-45%

Lime Slurry

35 - 25%

65-75%

Milk of Lime

20 - 1%

80-99%

Lime Water

0%

100%

Air-Slaked Lime

100%

0%

When the exact amount of water is reacted with quicklime (CaO) it will
chemically combine completely leaving a Dry Hydrated Lime which is
sold in bulk or 50 lb. bags. Whether a customer orders quicklime or hydrated
lime, in most cases, they will ultimately be forming a colloidal suspension of
hydrated lime in the form of either a Lime Slurry or Milk of Lime.
(Quicklime can be thought of as an intermediate product which will ultimately
be converted to hydrated lime.) From an industrial standpoint lime is
generally received by the customers in either bulk or bags as a dry product
(quicklime or hydrated lime). If quicklime is used it goes through a slaker
to be converted to hydrated lime and then slurried. If hydrated lime is used
it goes into a mixture which produces the slurry. In either case the customer
transports the lime within their plant as either a Lime Slurry or as a
Milk of Lime.

It is important to have lime in suspension (slurry) because of the low
solubility of hydrated lime in water. Lime Water is a lime solution
without solids, with the result that, when the hydrated lime that is in solution
is depleted, there aren't any solid particles to go into solution to replace
the lime that has been used up. There is some transportation of slurry
directly to customers by some lime companies, however, this is a relatively
small part of the lime business. Since a large portion of slurry is water, the
customer ends up having to pay for the transportation of water, which may
offset other savings associated with not having to make the lime slurry
themselves. Also, more trucks are required to deliver the same effective
amount of lime that can be delivered as dry hydrated lime. A standard formula
(guideline) is used to prepare suspensions of lime (Lime Slurries and
Milk of Limes) as follows:

Air-Slaked Lime is the reaction of moisture in the air with quicklime
(CaO). Quicklime is very hygroscopic and can be considered a desiccant. It
will absorb and react with moisture in the area to convert to hydrated lime.
Although this reaction is exothermic, air-slaking does not generate much heat
because the reaction takes place over an extended period of time. The biggest
problem from air-slaking comes from the effect on samples of quicklime. The
reacted water adds weight to the sample and decreases the percentage of
available lime. Samples of quicklime should always be sealed and tested
rather quickly. Lime Putty can be thought of as a thick, paste form of
lime and water. Usually it is prepared by customers and homeowners who need
the use of lime in this form.

When I receive a shipment of lime, by truck or rail, how long do I
have to unload it? Is there a penalty if I exceed the time allowed, and
what is meant by the term Demurrage?

Truck Delivery: The time allowed to unload a
truck, without penalty, varies with each carrier. Generally, you are
allowed one to two free hours to unload a truck, depending on the carrier's
policy. This time usually starts from
the designated delivery time, if there was a time specified. Otherwise, it
is from the time the product was delivered to the plant. The penalty is a
per hour (or portion of hour) charge.

Rail Delivery: In the case of hopper cars
(rail delivery), you are usually allowed two days for unloading. There is a
per day charge, which begins to escalate each day the car is held from
service. Each rail carrier has their own penalty time periods and charges,
so you will need to verify these with each rail carrier, as you do with
each of the truck carriers.

Demurrage:
In the trucking and rail shipment modes The term demurrage refers to
the penalty charge applied to the time period beyond the free unloading
time during which a penalty is applicable. This penalty is assessed because
the truck, or hoppercar, is withheld from transit to its next destination
or from the pool of available trucks or hopper cars.

Impact of Holding up a Truck:
Although applicable to both truck and rail shipments, holding up a truck
can have a significant, immediate impact. The reason for this has to do with
the availability of trucks. Often, a customer will have a requirement for
multiple daily truck shipments to their plant. Depending on the shipment
distance, and driver hours, the morning truck may make a turn around
and deliver another load in the afternoon. If the morning truck is held up,
it can result in a delay of the later shipment, since it may be the same truck
making that delivery. Trucking companies assess a demurrage charge/penalty
to get trucks back into service quickly, as well as to help offset the
expense of driver wages, since the truck has been removed from service
until it is unloaded. In reality, the trucking companies, as well as the
railroad companies, do not want to have to charge demurrage and would prefer
to get their truck or hopper car back into service, since this is how their
revenue is generated. The demurrage charge does little to offset the lost
revenue.

Historical origin and definition of the term "Demurrage": This word
originally came transportation by ships. The following description of
demurrage came from the 'Lectric Law Library Lexicon on Demurrage
- "The freighter of a ship is bound not to detain it, beyond the stipulated
or usual time, to load or deliver the cargo, or to sail. The extra days
beyond the lay days (being the days allowed to load and unload the cargo),
are called the days of demurrage. The term is likewise applied to the payment
for such delay, and it may become due, either by the ship's detention, for
the purpose of loading or unloading the cargo, either before, during or
after the voyage, or in waiting for convoy."

When I called to place an order for lime by truck I was told there
was a shortage of trucks. All of the lime companies I talked
with also confirmed this. Why does this happen? Also, how do the
trucking companies maintain enough trucks to serve the lime market and
what can I do to help avoid these truck shortage situations?

Lime is usually shipped in a pneumatic trailer, which is a
specialized tank truck with a blower that can blow the lime from the truck
into the silo of the customer. Because of the freight cost factor in
shipping lime, the lime market is generally a regional one, with most
shipments destined to customers in the state where the lime plant is,
and/or the adjoining states. A number of trucking companies include the
lime market in their transportation business, and acquire enough pneumatic
trucks to serve this market. The combined number of trucks available
continually adjusts to general market conditions, and can change, but
generally this involves assigning new equipment to the market area, which
can involve some delay. Also, any equipment moved to meet the demands of
the local market has to be withdrawn from another competing market area.
In any case, the number of trucks within a geographical lime market area
can be viewed as somewhat fixed over the short-term.

When a lime customer calls a lime producer for orders, that lime company
will call one of more of the truck carriers that handle the local lime
market, and set up a shipment schedule(s). For the most part, all of
the lime companies use the same commercial truck carriers, though some
carriers may be designated as the primary carrier for a customer.
Throughout any day the availability of trucks can vary, dependent upon
the demands of the lime market. Also, there are a number of industries
that can place tremendous, short-term demands on both the lime producers
and the trucking companies as a result of customer equipment problems,
production problems, unusual weather, plant startups, etc. In arranging
for trucks, it's not unusual to find that there are short-term
shortages of trucks throughout the day. But this can, and often does,
dramatically change during the day. Another key factor in truck
availability involves the Driver Time. Recent changes in the law
require that drivers can only drive for a specific period of time, after
which they must rest for a minimum number of hours. This becomes a
factor since there are only a number of total drivers serving a specific
lime market area. The trucking companies do their very best to try and
maintain enough drivers and pneumatic trucks to serve the local lime
market without having their drivers or trucks inactive.

Placing orders with a lime company as early as possible helps a customer
avoid many of the unanticipated problems associated with truck
shortages. However, much of the lime market involves servicing those
industries who have enormous short-term demands, which is a very
important and much appreciated business for lime companies. Those
customers who experience a short-term truck shortage may find solace in
knowing that the availability of trucks in the market is quite fluid and
changes frequently. For the most part, the lime companies are able to
meet the daily demands of the lime market during truck shortages through
the patience and understanding of the valued customer.

I am considering comparing getting my lime by rail vs. truck. What are some
of the pros and cons regarding these two modes of lime delivery?

Both modes of receiving lime have advantages and disadvantages. Following
is a list of points to consider:

Do you have a rail siding coming into the plant?
If you do not have a rail siding coming into your existing plant then
the option to receive lime shipments by rail is not available to you, unless
you are willing to provide rail access to the plant. In the planning of a new
plant it's important to address the issue of potential rail delivery of lime
during the early design stages. This is because rail delivery of quicklime will
require a railroad spur to the lime unloading site, an unloading system of
some type and adequate silo storage, usually at least a 150 tons. (For
reference, a hopper car of quicklime weighs approximately 100 tons.)

Are you using quicklime or hydrated lime? Pebble quicklime is
often carried via covered rail hoppercars while hydrated lime generally is
not carried via rail. Hydrated lime is a fine powder which would require a
special PD railcar (pressure differential). This type of railcar could also
handle a granular or pulverized quicklime. For the most part, unless the
volume of hydrated lime used is significantly high, it is usually carried
via pneumatic trucks. (As a general guideline you can consider that pebble
quicklime can be carried by pneumatic trucks or bottom drop rail
hoppercars, whereas hydrated lime is usually carried pneumatic trucks.
Please be aware, however, that there are exceptions to this.)

Truck Delivery Advantages and Disadvantages: Receiving lime by
truck offers an excellent and quick way to meet your lime requirements.
Assuming that the lime supplier has product available, the only time delay
is that of the setting up of the trucks and the travel time to your plant.
The lime is delivered from the pneumatic truck by blowing the lime into
your silo. The silo should be able to hold at least a full truck of lime,
however, it's better to have a silo capable of holding about two trucks of
quicklime (50 tons) lime to provide room for a recent truck order and to
provide a cushion in the event of a truck delay, or product availability
issue. Because a truck only holds about 1/4 of a railcar, you will have
about four trucks to every rail car. Also, if you are receiving lime from
a transloading terminal, you will be paying the cost of the transferring the
lime from a railcar to a truck, plus the cost of the truck freight to your
silo.

Rail Delivery Advantages and Disadvantages: Assuming that you
have a rail siding that is accessible to your plant, rail delivery offers
an excellent way to receive pebble quicklime. The freight rate is generally
lower than the truck rate, especially the further your are from the lime
source. Also, each railcar, which holds about 100 tons, is about
equivalent to four trucks of 25 tons each. As with truck delivery, there
are disadvantages to consider. There are initial costs involved with
extending existing rail sidings to allow access to the lime silo location.
A railroad switch has to be installed, as well as a rail unloading system
and adequate silo storage. Since most railcars hold about 100 tons, the
silo should be at least 150 tons in capacity; preferably larger. Also, rail
delivery requires planning. As a guideline, a delivery time of seven to
ten days is useful to use, though often it's closer to five to seven days.
As a result of the days required for rail delivery, planning of lime usage
is required. Since planning is an integral aspect of most plant
operations, this should not be an issue where lime usage is consistent and
relatively predictable.

Is Truck Delivery Best For Me? This is a question only you can
answer, however, there are some thing to keep in mind in considering rail
delivery. As a general rule truck delivery is most often considered when (a)
lime usage is very unpredictable (b) there is no rail access to the plant,
(b) the volume of lime used is relatively low, (c) no rail siding, switch,
rail unloading equipment adequate silo capacity is available nor is the
company willing to commit to the capital expenditures to provide for
these. (If only hydrate is used, only truck delivery is usually
considered.)

Is Rail Delivery Best For Me? As with truck delivery, this is
one that only you can answer, however, in considering rail delivery there
are some things to keep in mind. As a general rule, rail delivery is most
often considered when (a.) a relative high volume quicklime is being used,
(b.) the plant already has rail access to some degree, (c) and the company
has an existing rail siding, switch, rail unloading equipment and adequate
silo capacity in place or is willing to commit to the capital expenditures
required to provide these. (All plants have the capability to receive lime
by rail should be able to receive lime by trucks as well, which will enable
the plant to obtain quicklime on short notice when the usage cannot be
anticipated.)

I am considering using a Pressure Differential railcar (PD
Car) for lime delivery by rail. What kind of railcar is this and is
there any reason why I would not want to use this type of car?

The Pressure Differential (PD) railcar is a specialized railcar that
has the capability of blowing lime directly from the railcar to the silo,
in the same way that a pneumatic truck can blow lime from the truck to the
silo. It can be used for both hydrated lime and quicklime. For the most
part, quicklime is carried by bottom drop covered hoppers that require that
the lime drop into a pan under the car where it is then drawn into an
unloading system that then blows the quicklime into the silo. The PD car
appears to be a great alternative to using the bottom drop cars, however,
there are issues to keep in mind when considering this type of railcar.

The railcars used for quicklime are part of a Car Pool of
railcars designated by the railroad for lime. Lime suppliers request a
specific number of cars to be dropped off for loading. The quicklime is
then loaded into these cars and then shipped to the customers. Generally,
the railroads do not have PD cars in this pool of cars. PD cars are owned
by either the lime company or the customer. Even if the PD cars were
available for customer use, because the lime company owned some, or
the customer owned them, there can be a monumental logistical problem
involved with using PD cars. A customer that specifies the use of PD cars
would have to be certain the car had made it back to the lime plant in a
timely fashion. When they placed their order for quicklime the timeliness
of the delivery of their product would be dependent upon whether the PD car
was available. With bottom drop cars the lime company simply takes the
order for the car load and ships it as soon as car is available which may
very well be that day, or within a day or so (usually). With the PD car
there may be a considerably delay waiting for the PD car to be returned, or
made available (brought in) by the railroad.

In summary, using PD cars is not out of the question, but any company that
wants to consider them needs to keep in mind that these cars are not
usually part of the car pool and are not often used lime companies. They
also need to be aware of the significant logistical issues in using a very
specific car that must transit between the lime plant and the customer.

I am planning to starting ordering truckloads of bagged hydrated lime.
Should I have the lime delivered by a flatbed or van type of truck?

Generally, you only order bagged hydrated lime by a van truck (box) if you
have an unloading dock. Flatbed trucks are primarily used when there is no
loading dock available. A flatbed truck can be easily unloaded from the
side of the truck with a fork lift. (Unloading a van truck without a
loading dock is difficult and time-consuming. Each of the pallets would have
to be pulled to the end of the truck with a pallet jack and then removed
with the fork lift. Unloading a flatbed truck from a dock is dangerous
because the forklift driver runs the risk of driving off the open side of
the flatbed.)

When I order truck shipments of lime my lime supplier sets up the
trucking. Should I consider having my company handle the transportation
arrangements or should I continue to have my lime supplier handle this?

At various times lime users are faced with deciding whether to set up their own
trucks or have their supplier to do. Answering this questions requires
careful consideration of a number of key issues. Listed below are some of the
issues that need to be kept in mind:

Lime companies do not mind if a customer sets up their own trucks:
Setting up trucks for customers is a very important and integral part of the
lime supplier's business, however, any customer who handles their own
transportation frees the lime supplier from the scheduling of trucks, which
is always welcomed.

Advantage: Those lime users
who set up their own trucks do have an advantage in that they can have their
trucking company send in a trucks to pick up lime as needed. Often, the delay
the lime supplier experiences in not getting trucks out to their customers
right away is the result of trucks not being available. Having the lime
customer handle the transportation avoids this problem, however, those
companies that do set up their trucks need to be certain that product is
available before sending their truck in to load.

Disadvantage: The logistical issues of a lime user arranging a large
number of trucks from different trucking companies, however, may be a
difficult undertaking and they will need to make certain that trucks they
scheduled actually do arrive at the lime supplier's plant.

Lime suppliers have established relationships with multiple trucking
companies: Some lime users, such as those in the pulp and paper industry,
have unplanned, high volume needs for quicklime. During these periods of high
demand all of the regular lime carriers in a particular area are required.
Most lime suppliers already have established, ongoing relationships with
the carriers that are able to serve their plants. Because of this, it may
often be much more practical for the lime customer to allow the lime supplier
to handle all lime shipments.

A lime user may be able to negotiate a freight cost savings: In some cases a lime user may be
able to negotiate a better freight rate by dealing directly with the freight
company. A rate can be established with a particular carrier for the routine
shipments. During periods of high demand (planned or unplanned outages) all
of the other truck carriers can be used.

What is the difference between Short Miles and Practical Miles
in determining freight rates and why can there be differences between the two
mileages when going to the same location?

Short Miles and Practical Miles Defined:
Short miles represent the shortest distance between the origin and destination
that a commercial truck can travel. Practical miles represent the fastest
distance between the origin and destination and may be longer than the short
miles. Since truck lime freight rates are based upon the shipment (product
weight times freight rate), and not trip time, short miles represent the
lowest overall freight cost for the customer.

Historically:
The lime freight rates were based upon Rand McNally short miles.
In recent years a number of the truck companies have gone to an alternative
mileage source; PC-Miler. In comparing short miles for the two mileage
sources you will find them nearly identical since, assuming the road
information is up-to-date, the shortest commercial truck distance between
the origin and destination is simply a matter of adding the distance of each
segment of the trip; which is a fundamentally simple algorithm to compute.

Conversion to PC-Miler:
In the conversion to PC-Miler some of the trucking companies have made
the decision to use practical miles rather than short miles. This presents the
customer with a dilemma. To see the problem envision four truck carriers with
nearly the same scale tariff rates, with two of the carriers using short miles
and two using practical miles. On the surface they would all appear to have
nearly the same scale rates, however, since two of the carriers use practical
miles there are often instances when there is significant difference in total
truck cost due to the difference in short and practical mileages.

Analogy for Short and Practical Miles:
A lifeguard rescuing a swimmer offers a good overview of short vs. practical
miles. A lifeguard watching over swimmers knows that he can run much faster
on the beach than he can swim in the water, so he takes this into account in
his rescue plans. If the person to be rescued is in the water directly in
front of his lifeguard chair he simply runs to the edge of the water and
swims directly to the swimmer. (In this case the shortest and fastest
distance are equal.) As the position of the swimmer moves further and
further up or down the beach the difference between the shortest and fastest
options begin to increase. Generally, the lifeguard would run down the beach
to a point where the swimming distance is minimized then enter the water and
swim the shortest distance in the water to the person. Often, in these cases,
the quickest distance is longer, although faster.

Factors for a Carrier to Elect to go to Practical Mile:
Because of the change in the hours of operation for a driver, going the
quickest route, rather than the shortest would appear to help preserve driver
hours. However, the extra distance requires more fuel, which offers an
offsetting disadvantage. Also, the algorithm used in determining practical
miles is more complicated and subjective than short miles algorithms since
they involve driving speeds, traffic congestion and road construction. These
can vary far more frequently than the simple short distance to the destination.
Also, the discrepancy between short and practical miles makes it difficult to
compare carrier rates. As a final note, it is unlikely that the truck drivers
would not elect to take the shortest route, even if it were longer than the
practical miles route.

What is a Carrier Solution to the Problem?
All truck carriers would be far better served to use the traditional standard
short miles (Rand McNally, PC-Miler or alternative mileage
sources) so that significant mileage differences are no longer an issue.
If the carrier believes that the short miles do not provide enough truck
revenue for the haul then they can simply increase their tariff scales rates
to offset this.

What is a Customer Solution to the Problem?
There is a relatively simple method to solve this problem. If the largest
carrier uses short miles, then all shipments by all carriers are based upon
short miles. Rates of carriers continuing to use non-short miles would find
that all of their rates are now determined on a point-to-point basis, and
ultimately then end up with all point-to-point rates.

I have had a railroad issue with CSX Railroad which has resulted in the generation
of a case number. If they have to contact the trainmaster, how long do they have
to get back to me?

The short answer is up to four hours. An example of why this time is needed involves
the trainmaster. If they have to contact him that person may not be able to respond
for up to four hours due to operational responsibilities. The railroad designate enough
time to cover most delays, however, their goal is to respond as immediately as possible.
(An analogy would be FedEx's two day guarantee delivery service. They guarantee the item will be delivered
in two business days, however, they will deliver this the next day if possible.)

When I try to view a PDF file in my browser it does not appear. All I get is a
small icon on a blank page. Why does this happen and how do I correct it?

Many people use Adobe Acrobat to view PDF files while using
their browsers. The PDF file is automatically loading into the browser as
as a web page. Sometimes a problem can arise in viewing PDF files this way
because of issues involved with the integration of the browser and the Adobe
Acrobat viewer. To solve the problem: This problem can usually be
eliminated by going to the Adobe Acrobat viewer preferences and disabling
the "View In Browser" option. All PDF files will then load separately
into Adobe Acrobat.

Why are all the Questions and Answers on the FAQs (Frequently Asked
Questions) web page displayed on single page, rather than on multiple pages
of the web site?

By having all of the FAQs, (and answer sections) on one page, a person wanting
a hard copy of all of the information, without using the PDF file provided,
can simply print the entire FAQs web page and place it in a file for
reference. Having the information on multiple web pages would require the
person to go to each specific page of interest, and print that one particular
page, then go on to other pages. Individuals wanting just a limited
amount of information from the FAQs web page can cut and paste that
information into a word processor, or simply print the pages of interest
from the PDF file provided.